Having not tried it, and not having a myspace (well, I do, but I never use it... ever ), looking at the script I would say it notifies you on New Mail, friend requests, bullitins, events, and blogs.
It looks as tho it adds these to a drop down in the Plus! menu, and you can click them and it will let you know if you have any new notifications.
Just a guess, and if this is what it does, well done BstrdSmkr ! Very cool. Like a personal RSS
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), looking at the script I would say it notifies you on New Mail, friend requests, bullitins, events, and blogs. 
! Very cool. Like a personal RSS 
