She will always be able to get a cosmogirl, seventeen and even Teen Vogue. I will be suprised if she is not on the cover of either TV or Seventeen in 2009... she's only 22.
Cosmo is not her first adult cover, she has been on Shape mag earlier this year... I think. But yeah, Lucky, Self, and even Nylon or HB are not out of her reach... especially since she is branching into scripted TV now.
It would also not be a bad idea for her to do a FHM or Maxim cover. She can still be tasteful but sexy. Hilary Duff spread in FHM was excellent imo.