Using Chrome (7.0.517.41 beta) on Ubuntu 10.04 LTS.
When I type in the chat, and my sentence happens to extend beyond the confines of the text entry bar, the rest of my sentence disappears. A screen grab:
i.imgur.com/mCuwR.png
From the chat, I had typed: "Here's an example sentence, just so I can take a screen grab to send"
...And from what you can see in the screen grab, everything after "I can take a ..." is missing.
Workaround: Press Shift+End to highlight the sentence, moving the cursor to the end of the line. Not pretty, but it works.