How are you sending them a PM, typing it in directly, from their profile, buddy list? I did make some changes to this for 7.0.1 to stop the javascript (duplicate) bug.
Their name is in the 'Add Recipient' box and the brief second between the submit and the actual send it looks like it puts them into the send line... I'll see what happens when I try to add them in.
hmm... I hadn't clicked on the 'add' button, maybe the default action should be that if I click on the drop down message to send them a pm they should be in the send line, then I can add people if I like.