Hi Trux! to ATP. That sure is a beautiful little cactus but I don't know cacti so I can't help with an ID but hopefully someone more familiar with them will come along soon and be able to help.

It's almost certainly a mammillaria, as for the species, I do not know!

It shouldn't be TOO hard to properly id, but there's ALOT of mams.

this is very helpfull http://cactiguide.com/habitsea...
if not try to post pics at http://www.cactiguide.com/foru...
for my money i second mammillaria
good luck

Rosemarie posted on the cactus and succulent forum and I'm copying and pasting her comment below:

[Okay, somewhat difficult to say...I believe it is a type of Mammillaria. It looks to be dichotomous (branching-splitting into 2 heads). Mammillaria perbella & ,parkinsonii are known to do this (although they are not the only ones). They are both variable. I think M. perbella has darker pink blooms, so I'm leaning toward M. parkinsonii. This is a very large genus, so that's my best educated guess.]

I googled and found this photo for comparison: