A few people have been asking me about AS3 these days, so I thought I would share a couple of resources that really helped(and still are helping) me.

This post on Kirupa has been an amazing resource for the Actionscript 2 to Actionscript 3 migration.
http://www.kirupa.com/forum/showthread.php?t=223798

This AS2 to AS3 migration cheat sheet helps a fair amount as well:
http://actionscriptcheatsheet.com/blog/quick-referencecheatsheet-for-actionscript-20/