Google Wave is now open to the public as a Google Labs project and to Google Apps users, subject to administrator approval.

Google plans to announce the general availability of Wave at its annual developer conference in San Francisco on Wednesday, where the real-time communications platform debuted a year ago to considerable fanfare.

Wave is at once a product, a platform, and a protocol. It combines the functions of e-mail, instant messaging, wikis, and blogs in a framework that facilitates both real-time and stored collaborative messaging.

Initially described by Lars Rasmussen, the Google engineer who created the project with his brother Jens, as an attempt to re-imagine e-mail for the modern era, Wave must confront skepticism that has arisen about its usefulness.

The proposition that Wave might replace e-mail and instant messaging now that seems as naive as the notion that Segway scooters, once known as "Ginger," might prompt people to abandon their cars and re-architect their cities.

Beyond a more convincing value proposition, Wave needs users -- the invitation-only beta test didn’t bring in the critical mass of people necessary to promote widespread collaboration. Opening the service to the public is the first of many steps that need to be taken for the service to thrive.

Another step is partner involvement and that starting to happen. Not only has Novell embraced the Wave protocol for its Pulse enterprise collaboration service, but SAP plans to announce support for Wave federation in its StreamWork collaboration product.

Google has improved Wave significantly since its preview release to developers. Features like e-mail notifications about new and changed Waves, and browser add-ons that serve a similar function, represent a good start, even as they acknowledge the primacy of e-mail.

Wave is also more stable, and easier to navigate, with new APIs, an extension gallery, and support for public Waves that can be embedded in Web pages.

"We think we're at a place where Wave is mature enough where real work can get done and you can really see the benefits of doing your work in Wave over existing tools," said Rasmussen in a phone interview.

Wave's sweet spot, says Rasmussen, has proven to be collaboration. "The first place we've found that Wave shines is scenarios where groups or teams are working on projects together," he said.

Rasmussen and his team acknowledge that they've learned a lot over the past year about Wave’s shortcomings and that they still have more to do to address enterprise needs related to regulatory compliance. But they're confident enough in the state of Wave to open the service up to all comers.

"If you tried it earlier and found it's not ready, give it a spin now," suggested Rasmussen.

The Enterprise 2.0 Conference is the largest gathering for people ready to connect teams, and harness collective intelligence with social tools and 2.0 technologies. It happens in Boston, June 14-17. Find out more here.