On the "Ask Question" page, the Title input box initially contains "What's your programming question? Be descriptive." in grey text. Typing text erases the prompt and displays what you type in black text.
However, pasting text into the input box doesn't trigger the erase, inserts the pasted text into the prompt, leaves the text grey, and typing any further text doesn't trigger the erase either.
The same thing happens on other input boxes that contain initial grey prompts.
Browser: IE 7.0.5730.13
Update: This appears to be an IE-specific problem. I wasn't able to repro it in Firefox or Safari.