Hey I mentioned months ago (right below) how to get RB2 sogns on RB3.
I got RB3 for xmas and did those exact steps on xmas day... and it said it was all good but nothing happened, i was never prompted to rip sings from a disk or do a download, i dont think they are in RB3 :S
Hey I just noticed the thread about RB3 and exporting RB2 songs, sorry I didn't reply sooner but I was correct, you use the code on the back of the RB2 manual to export them.
Exporting Songs from Rock Band 2 (PlayStation®3)*:
Enter the code from the back of your Rock Band 2 manual where prompted. (Note: This will be the same code that you used to get the “Bonus Downloadable Tracks,” but the web address is different.
Copy down the code given to you from the website for use in Rock Band 3.
Load up Rock Band 3.
Select “Get More Songs” from the Main Menu of Rock Band 3.
Select “Redeem Code.”
Enter the code that you received from the website.
NOTE: International players should enter the first 16 digits of their code directly into their console.