No Aerosmith songs being moved over I guess... but weirdly, Metallica will be in RB2.
What's funny is that apparently the Rock Band drums will work with GH4. Maybe Activision is learning to be friendlier... or maybe they'll have constant reminders during the gameplay: "This would be so much cooler with official GH:WT drums, bitch!"
The only problem with Rock Band is that now I will have to get the hard drive addon. Almost makes me wish I bought the PS3 version.