Google Wave's inbox, as seen on the Official Google Blog. (Courtesy Google) In May, Google announced Wave, the company's attempt to reinvent internet communication. Brothers Lars and Jens Rasmussen, the Australian creators of Google Maps, have been working on the project for the last two years.

On Sept. 30, Google opened its preview of Wave beyond the 6,000 or so software developers who are currently helping to build the service. About 100,000 users can now see what Wave is all about.

Google Wave incorporates ideas from email, instant messaging, blogs, wikis and bulletin boards into a single new method of communicating. But we already have email, IM, wikis and the rest, so why do we need one tool that does all of these things? What is new in Google Wave?

Live editing by multiple users

In their first demo of Wave at the Google I/O conference, the project's lead engineer, Lars Rasmussen, and project manager Stephanie Hannon demonstrated how a conversation that starts out looking like an email, with replies going back and forth, can turn seamlessly into an instant messaging conversation if more than one person has the wave open at the same time.

Actually, the conversation is even more instant than instant messaging. Each key stroke by every participant in the wave is visible to all the others as it occurs. Rasmussen said this would result in faster communication than IM because you wouldn't be spending half the conversation waiting for the other person to hit "Enter."

However, he seemed to recognize that not everyone would want to communicate in this way, and said that a wave's settings could be changed so that messages are only sent after the user hits "Enter."

This live communication isn't limited to IM-type conversations. Anything in a wave can be edited by anyone who's been invited into it, including the original message. In the demo, colour-coded cursors, labelled with their owners' names, race around a document, all making changes simultaneously.

Playback

You can add people to a wave at any time, in much the same way you can forward an email. But someone coming into a wave after three other people have discussed and collaborated on a document might not see right away how the conversation went.

To address this, each wave has controls to move back and forth through time to see all the changes to the wave in the order they happened. Every wave stores the history of changes that have been made to it, in same the way a page on Wikipedia has a history, making the playback possible.

Drag-and-drop adding of files

Instead of attaching files as you would in an email, you can drag and drop files directly into a wave conversation. Google Wave's Stephanie Hannon showed how several people could contribute to a group photo album by dragging and dropping the files from the desktop into a wave. (She pointed out that HTML 5 doesn't yet support this function, and it required a browser plug-in called Gears to work.)

Dropping Word documents, spreadsheets or slide presentations into a wave could make collaborating on a project simpler than email, where tracking different versions of such documents can be challenging.

Embedding

A wave can be embedded on to a blog post (or any web page) in the same way a Google Map can. Changes made to the wave are immediately seen in the embedded version. In this way, a wave can act like a comments section on a blog post or a web-based chat room. A photo gallery created by you and your friends can be posted on your blog for everyone to see.

A sudoku game being played inside Google Wave. (Courtesy Google)

Extensions and applications

Developers can write their own applications that run inside Google Wave, in the same way that third-party applications run inside Facebook. In the demo, Wave's developers showed how a chess game would unfold inside a wave, complete with the playback feature to show each move in order.

A Sudoku game inside a wave becomes a competition to see who can fill in the most squares correctly. And because the team behind Wave also built Google Maps, they showed off a Maps gadget that allows two or more people to mark locations on the same map at the same time.

Natural language

Lars Rasmussen demonstrated a different kind of spell checking in the demo of Google Wave, one that uses a natural language algorithm to detect misspellings rather than a dictionary. The spell check found the errors in the sentences: "Could I have some been soup? It has bean too long." The natural language model was built using the entire web as a template, putting the technology behind Google's search engine to use.

One of the most impressive Wave features that Rasmussen demonstrated was an application called Rosy, which translated his words to French from English as he typed in a wave. A colleague wrote back in French and his words were translated to English for Rasmussen to read.

Open-source protocol

Google Wave isn't just a Google product. The Wave team has made Wave an open-source protocol so that anyone will be able to set up a wave server. Every wave server would be able to speak to any other, in the same way that you can send email to anyone whether they're on Gmail, Yahoo, Hotmail or a corporate email server.

Making the project open-source also invites developers to write their own extensions and applications to work inside Wave, and to improve the service itself.

Wave has generated considerable buzz online since its introduction in May. Some tech blogs have declared that Wave will "change everything," and have heralded the death of email.

Others in the tech world aren't as enthusiastic. Microsoft’s chief software architect, Ray Ozzie, has called Google wave too complex and "anti-web."

"It violates one principle that I hold so true right now, which is complexity is the enemy in the ethos of the web," Ozzie said in June at a discussion on cloud computing in Palo Alto, Calif.

Ozzie praised the Google team for taking on such a complex problem. "I love it when people think big," he said. "But I think the complexity is an issue, and they had no choice because the problem they took on — the way they defined it — is an inherently complex problem."

Ozzie is biased, of course. He developed Microsoft Groove, an application for collaborative document creation.

But because so few people have seen Wave for themselves, there are many questions still left unanswered. Waves and emails will presumably co-exist for a long time after Wave is finally released to the public, but it's unclear from the demos how the two systems will interact.

Privacy is also a concern: How will Wave handle the embedding of a private conversation on a public web page? Will every person involved in a wave have to consent to its publication?

And while the group editing of wikis has made sites like Wikipedia possible, they also introduce unique problems. Would Wave introduce Wikipedia-style edit wars to everyday conversations?

We'll know more when Google rolls out the next wave of Wave later this year.