I'm having an issue with my keyboard not popping up too, but I didn't see a fix here. I only use portrait mode, and I have the problem in Google Talk, and using my Handcent SMS app. It just started acting up since I did the 2.1 update, and almost every time I receive a message while my phone is asleep, and I go to respond to a text, I have to hit the menu key on my screen twice, select the text box for the reply again, and then the keyboard will pop-up.
On occasion it won't pop up at all, so I have to exit out of the app, and then go back in for it to work. This is severely annoying, and I'd rather not do a factory reset - please help!