I don't think that they can be reversed for good, but I think they can be "reversed" for a little while. I heard on "Regis and Kelly" that there's this cream called "Crease Release"... it's supposed to smooth your wrinkles, crows feet, etc. And there's another lotion/cream I heard about called Strivectin that's supposed to do the same thing.
I heard great stuff about the latter. Haven't tried either one because they're a little costly for me right now. But if you have cash, or are desparate, then you might want to try it.