I tried out the free version of this software a couple of months ago and loved it until it expired. It at least doubled my typing speed compared to the standard keyboard on my HTC Desire. But I didn't want to fork out the $8 they were charging at the time for the full version.
It's now available from the SlideIT site, and the Android market for US$3.99.
According to their website "This promotion is only available for a few days".
Here is a review from PC World: http://www.pcworld.com/appguide/app.html?id=464245&expand=fa…
Swype is free!
http://beta.swype.com/