Here's a thread about AutoText. And, better yet, here's a place that you can vote for it.

However, for some reason it's listed there as "invalid" -- I don't know what is meant by that, and I'm finding Brainstorm takes forever to load. Anyone else able to shed some light?

I think this is a great functionality for the N900 to have (heck, I wish Diablo had it!) and is worth fighting for. If you have doubts, read the above-mentioned thread, especially posts #1 and #14 by zkyevolved.