When Google Wave invitations first went out, they were hugely popular, with requests appearing left and right and bids topping $5,000 in one eBay auction.  Now, perhaps with the hope of creating a second surge of excitement, Google’s done away with the invitation system, opening Google Wave up to everyone (including Google Apps users).

Obviously, the overall situation’s changed in a couple ways since last October; a lot of people have tried Wave and decided they don’t care for it, and Twitter, which might be considered a competitor of sorts, has become a more firmly entrenched part of everyday life.

Still, Google’s trying hard to win over skeptics.  Lars Rasmussen, who’s considered a cofounder of the Google Wave effort, was on hand at Google IO to break the availability news in front of a large audience.

Also, Stephanie Hannon, a product manager, wrote on the Google Wave Blog, "If you tried Google Wave out a while ago, and found it not quite ready for real use, now is a good time to come back for a second try.  Wave is much faster and much more stable than when we began the preview, and we have worked hard to make Wave easier to use."

(Hannon then specified, if you’re curious, "For example, you can now get email notifications when waves change, easily navigate to unread parts of a wave, and remove participants added by mistake.  We have also added permission management options and an extensions gallery.")

So we’ll see what happens next.  And one key point, whether or not Google Wave is successful at finding a sizable user base this time around, is that the product remains a part of Google Labs, so additional changes and refinements may be on the way.