The logo, or the headlines on the cover?

the main logo

from any time period, I assume its changed over the years...

this thread has your answers.

http://www.typophile.com/node/2804

haven't seen RS in the past year, but last I checked, they were using a lot of stuff from
Frantisek Storm — most notably Farao.

http://www.stormtype.com/

Before that, iirc, they were using a lot of Hoefler's Proteus type.

http://www.typography.com/fonts/font_overview.php?productLineID=100019

you'll read about Parkinson in the other thread, but here are the links:

Parkinson
http://www.typedesign.com/

and Dennis Ortiz-Lopez
http://www.ortiz-lopez.com/

Custom type for Rolling Stone Magazine by Deniz Ortiz-Lopez:
http://www.ortiz-lopez.com/OLP19.html
http://www.ortiz-lopez.com/OLP20.html

Thanks guys- but I'm looking for a font I can actually use, that mimics the famous logo, not the body or interior type.

You're going to be hard-pressed to find an exact match, but maybe something like Casey from Font Bureau would work?

you might try Benicia as a starting point ...

http://www.myfonts.com/fonts/parkinson/benicia/black/

more RS work from Ortiz-Lopez:

http://www.ortiz-lopez.com/Digital2Part1.01.html