Have you tried booting and holding R for the recovery menu (if it got that far into the install)?
*edit* if it loads, you may be in luck.
Sorry johnsmith. I've gotta get some sleep in before work. I have another 14 hours ahead of me again today (starting in about 5 1/2 hours). I'll check back in when things are slow at work.
Night everyone. Good night, good luck.