I didn't mention this before because I thought the problem would be resolved by now and instead I just posted it on Mobitopia. I'm having Domain issues switching servers. Everyone one of my 20+ domains had no problems with the move, except one. Mobitopia, the most popular one. Joy.
The idea is that I was using Register.com's name servers instead of pointing it at my ISPs, usually because the ISPs UI for changing DNS entries normally sucks. But RackShack's is very clean, so after waiting 2 days for Register to update (and not doing so) I wacked their name servers and pointed the domain at RackShack's.
This'll take a while to process, but Mobitopia will come back soon, promise.