Interesting--I think this problem is limited to HTML textareas, the large text-input controls that you use to enter long text. I do not see this problem in the email app, the notes app, or the browser when entering in URLs in the location bar or short bits of text in HTML input controls like a username/password box. However, in Gmail, Blogger and this forum's post interface, I've been able to reproduce the problem every time.

In fact, I tried to post this message from my 770 using the keyboard to illustrate what sort of characters I'm seeing, but my 770 crashed when I pressed Preview Post. The crash may just be a coincidence, though--I had some network errors just before the crash, and my 770 has crashed a few times immediately following network issues.