Updated

—The iPhone costs $499 (with 4 gigabytes of flash memory) and $599 (8 gigabytes). A two-year voice and data service contract from AT&T Wireless is required. Phones will be available only at Apple Stores, AT&T-owned and -operated retail stores and the Apple Web site beginning at 6 p.m. local times in the United States only. Sorry, Canada.

—The iPhone runs on the GSM cellular standard, meaning it will never be compatible with Verizon Wireless's or Sprint Nextel's networks, which use a different standard. It's possible it could run on T-Mobile's network once the 2-year AT&T contract expires.

—There are approximately 170 Apple Stores across 35 states in the U.S. Each will close its doors from 2 p.m. to 6 p.m. Friday local time to prepare for the iPhone launch, as will the AT&T Wireless stores.

—Two new Apple Stores, in the Woodland Hills Mall in Tulsa, Okla. and the Bayshore Town Center in Glendale, Wis., will be opening their doors for the first time at 6 p.m. Friday night.

—It's not clear exactly when Friday the iPhone will go on sale at the online Apple Store — 6 p.m. Eastern time or Pacific time, that is. It's possible Apple could figure out in which time zone each buyer is, though if that were the case, it would be easy for a hacker to "spoof" an IP address in an earlier time zone.

—Most cell phone- and electronics-industry experts expect prices for the iPhone to drop significantly by Christmas.

—The iPhone has a 3.5-inch (measured diagonally) full-color LCD touchscreen. There is no physical keyboard; virtual number keypads or text keyboards pop up as required. Applications include MP3 and video playback, Apple's Safari Web browser, e-mail, text messaging, photo viewing, as well as cell-phone functions. It has a 2-megapixel digital camera, but does not as of now record video.

—Voice connectivity is via AT&T's GSM network. Internet connectivity is via AT&T's EDGE data network or local Wi-Fi hotspots; the initial versions of the iPhone will not connect to AT&T's faster HSDPA data network, though that will almost certainly be included in later versions. Bluetooth connectivity will link the iPhone to similarly enabled devices, but it is not clear if Internet access can be achieved this way. Nor is it clear whether some sort of Voice over Internet Protocol telephone service might be possible through the Safari Web browser.

—In a first for the cell-phone industry, the iPhone will not be activated in-store. Instead, each end user will need an online iTunes Store account to activate one of several AT&T service plans. Holders of existing AT&T wireless plans will be able to keep their old numbers, but will still need iTunes. The iPhone will not work, even as a music player, without cellular-service activation.

—The iPhone is compatible with iTunes running on Mac OS X 10.4.10, Windows XP Home or Professional with Service Pack 2 and all versions of Windows Vista except Windows Vista Home Basic. Connected PCs will need a USB 2.0 port.

Links:

Apple store locations: http://www.apple.com/retail/storelist/

AT&T Wireless store locations: http://www.wireless.att.com/find-a-store/iphone/

iPhone details: http://www.apple.com/iphone