Maybe it's browser specific? I'm using Firefox 4.0.1. When I edit an email, and select a bit of text in my reply, and try to drag it to a new location in my reply (say, to re-order a couple of paragraphs), I can't drop the text into a new location. As soon as I start dragging, the address/subject area turns into a big target labeled "Drop files here to add them as attachments" and I cannot release my text in a new location within the edit box. Works just fine in non-GMail pages (such as this forum). I can't even select text in one box, and drag it into a new box (which I used to do when I wanted to move someone's address from the To: field, into the Cc: field, or vice-versa).

And, while I'm on the subject, GMail seems to have stopped working for me in Safari. Not sure what version -- I'm not at home on the Mac, ATM -- but it's OS X 10.6.something.