Answering the eternal question "Do I need to stay up wicked late tonight/get up at the crack of crack tomorrow so I can get my iPad 2 order into the system as quickly as possible?", Apple has delivered a press release this morning with the details. Online orders will kick off at 1 AM Pacific Time tomorrow -- that's 4 AM on the East Coast of the US, and various other times around the globe.
Keep in mind that only US orders are starting tomorrow; wider international availability for iPad 2 begins on March 25, although if you have a US credit card and shipping address you can order from anywhere.
In-store availability for iPad 2 begins at 5 PM local time on Friday afternoon; in addition to the Apple stores, iPad sales will be ongoing at AT&T, Best Buy, Target, Verizon Wireless and Walmart stores as well as some Apple authorized resellers. Anyone buying their iPad at an Apple retail store will be offered free Personal Setup service, which includes email config and App Store registration -- you can use it on the way home.