The Google Wave product preview will be expanding beyond developers on September 30, 2009 adding another 100,000 users in addition to the developers currently using Wave.  According to a recent post on the Google Wave Developer Blog, the new users will be added from people who signed up and offered to test and report bugs.

So far, 6000 developer accounts have been activated for developers who wish to create projects using the Google Wave APIs.  The developers have come up with some interesting Wave gadgets as well as some nonsense which were presumably exercises for developers getting familiar with the APIs only.  The complete list of gadgets submitted along with source code can be found in the samples gallery.  A few notables highlighted in the Google Wave blog post are:

Groupy-the-bot: A robot, written in Python, that enables users to create groups and manage their own subscriptions.

Floodit Game: A competitive gadget game where users take turns capturing as many squares as possible.

Waves in WordPress: A neat use of the embed API that makes it easy to put waves in a post or page on WordPress.

Google Wave is truly a fresh innovative approach to electronic communications.  It stands to impact email, forums, instant messaging, blogs and who knows what else.  Google was smart to provide APIs and get outside developers involved from the beginning.  It will be interesting to see what impact Wave will have on the mainstream.