Outlook 2007 TR2 has changed the UI for a mail message, to make it more like Word; a ribbon tab for formatting text, and Paste in the key top left position. That's where Send used to be in previous beta versions and now I'm pasting whatever is in the clipbaord into wherever my mosue happens ot be when I go to send the message. Send is now *below* Paste, on the line with the address. It's as big as Paste but not as colourful, which is *wrong* because it't the most important action for a mail message. Yes, I've learned my muscle memory on betas that not all the Office 2007 users will have been using, but I learned it so easily that I think it was more logical. If Send is going to be on the address line, maybe it should be on the right - because sending comes after putting in the address and I read from left to right... close is over there already, so I already associate that with getting rid of the window.
Interface design is hard and many of the iterative changes in the 2007 Office betas have been improvements, but I am finding this change a real pain in the (Paste random content here) Send button