I have an Antec P180 as well, and I hadn't even thought about it not fitting. I don't see why it wouldn't, but hopefully I'll be able to find out this week. I also ordered an EVGA 7800GTX, with possible plans of expanding to SLI soon.
ISorm customer support said that Asus is expecting it's delivery from China on the 19th, and will ship them out directly from California. I'm very hopeful that this date will not change, and as of right now the isorm website has not changed its ship date. Fingers Crossed 🙂
EDIT: Also, with all these other stores starting the preorders, seems to me like it may finally be coming close to shipping.