This seems to be all over lately:
http://www.tablespoon.com/recipes/rainbow-tie-dye-surprise-cake/15086094-ad54-4d4f-82b3-68bffd7a0c9a/
I actually book marked it ages ago ('cause I'm cool like that!

) b/c my son REALLY wanted it for his birthday. Well, birthday celebration is coming up, and I'd totally forgotten about it until I saw it on a friends' FB feed. DS of course came by right then and said "hey - it's my cake!!!" so he's obviously still excited about it.
It seems so easy four months ago when I had plenty of time to experiment. NOw I'm not sure I have the time or energy to make 2 cakes in 3 weeks just to make sure it comes out alright for the party.
Have you tried this? Did it turn out well? Any tips or tricks?