I know there are 2 other threads for this but, I noticed a release date - Available for Xbox 360 and PS3 on September 28, 2012 (Europe & Australia)
and Pricing -
PC = $79.95 incl. GST
Also a version where you can buy a guitar if you don't already have one for $229.95 incl. GST
All are pre-order-able from http://rocksmith.ubi.com/rocksmith/
Great for practicing songs you like and for parties etc etc...