Normally (if they're not overloaded and they are atm) 2-3 business days (keep in mind this excludes all banking holidays, and sat-sun).
So it seems to be taking longer now. I wonder if I see my money at all.
Today is Wednesday, if you sent your request on thursday afternoon its been 2 business days. If you're in doubt file a support ticket.
I so far never experienced any problems with them, and support at mtgox always responded quicker than i expected.