We aren't taking single-day or 2-day pre-regs as far as I've heard about it. Then again, if you're pre-registering for 2 days, even a full-weekend con pass bought at the door is going to be the same price as a pass for 2 individual days (or possibly less, depending on which days you pick).
Basically, if you're planning on being there one day, buy your ticket at the door. If you're gonna be there 2 or more, you're better off pre-registering, as you'll come out ahead, even if you're not there the whole time.
PezCat