I saw this on a vbulletin forum ... when you recieve a pm its drops from the top of the page and sits bellow the navbar and it blinks.
and when the message is read its goes away.
--------------- Added [DATE]1250904170[/DATE] at [TIME]1250904170[/TIME] ---------------
solved! if you like to know how i did it let me know.But I could not figure out how it moves down the screen though.