Both U.S. carriers and all 236 Apple stores in the U.S. will start selling , with its front- and rear-facing cameras and 9.7-in. screen, in stores at 5 p.m. (local time) Friday. Expect lines if you're going to show up at a retail store.

Apple and AT&T will begin online sales at 1 a.m. Pacific (4 a.m. Eastern); Verizon will begin telephone sales at 5 p.m. Eastern.

If you're getting the Wi-Fi-only model and don't care about 3G access, your best bet may be the nearby Apple store or Apple's online store. That's because AT&T and Verizon both say they will only have the pricier models with both Wi-Fi and 3G access.

If you want the iPad 2 with 3G connectivity, both major carriers are offering 3G data plans without a contract, although the . AT&T will allow you to prepay for data with a credit card or to post-pay on your monthly phone bill; Verizon still requires only prepaid data purchases.