The SwiftKey keyboard for Android has come out of Beta and official version is available on the Android Market for 60p but only until 30th September 2010 then the price goes to it's normal £2.50.
I've used the Beta version for a few months and generally found it pretty good (better imho than the default keyboard). A number of people say that SWYPE is better and faster - I've not used that so can't comment and it's not available for users to download so it's not really an option.
The main selling point of the SwiftKey keyboard is that it supposedly scans your existing SMSs to determine your writing style and then suggests words it believes you are going to type based on context. It took a bit of time to get used to it but once you do it works well; when I briefly went back to a default keyboard I found I missed it a lot!
Hopefully useful to some of you new Android owning folks.