It’s finally here. Apple’s revolutionary iPhone goes on sale today at Apple Retail Stores, AT&T retail outlets, and through Apple’s online store. Long shrouded in secrecy, the final pieces of the iPhone puzzle were revealed this week in a carefully planned media blitz. Lucky tech writers for major media outlets who have been stealthily putting the iPhone through its paces over the last few weeks have broken their vows of silence and published their impressions. Their verdicts?

Walt Mossberg of The Wall Street Journal calls the iPhone “a beautiful and breakthrough handheld computer” whose “gorgeous screen makes other smart phones look primitive”. David Pogue of The New York Times says the iPhone is “so sleek and thin it makes Treos and Blackberrys look obese”. Steve Levy reports in Newsweek that “the iPhone is a significant leap. It’s a superbly engineered, cleverly designed and imaginatively implemented approach to a problem that no one has cracked to date: merging a phone handset, an nternet navigator and a media player in a package where every component shines, and the features are welcoming rather than foreboding. The iPhone is the rare convergence device where things actually converge".

Early adopters (yours truly included) will certainly converge on iPhone outlets today in veritable droves. A line began forming as early as Monday in front of Apple’s retail store on Fifth Avenue in New York. iPhones are already listed for as much as $1500 on eBay, and some enterprising folks are offering to wait in line for you for $300.

So what will the iPhone cost? The 4 GB model will set you back $499. Doubling the memory to 8 GB fetches $599. Seems pretty steep until you factor in the AT&T service plan prices, which are actually highly competitive with similar plans for their popular Blackberry phones.

Activating the iPhone requires a two-year contract with AT&T, just as with their other smartphones. AT&T offers three basic iPhone monthly plans, which all include unlimited data, visual voicemail, rollover minutes, mobile-to-mobile minutes, and 200 SMS text messages. For $59.99/month you get 450 minutes and 5000 night/weekend minutes. For $79.99 you get 900 minutes and unlimited night/weekend minutes. For $99.99 you get 1350 minutes and unlimited night/weekend minutes.

The overall two-year cost for a 4 GB iPhone, including the $36 activation fee and the mid-range $79.99 monthly service fee, will be $2419. AT&T’s Blackberry Pearl costs $2429, and Blackberry Curve weighs in at $2479 for the same period.

Here’s a nice touch. You won’t have to wait around and activate your iPhone where you bought it. You just walk in, buy it, take it home, and hook it up to your internet-connected Mac or PC. All of the activation steps are handled through Apple’s iTunes software - a new version (7.3) which will show up before Friday. You can choose to transfer your old phone number (which could take from 20 minutes to several hours, depending on the phone company you’re transferring it from), or get a new number.

Once your iPhone is activated, iTunes can transfer your selected music, movies, TV shows, podcasts, and photos onto the iPhone, and sync them in the future similar to the way it manages your iPod. As the iPhone only has up to 8 GB of storage space, you’ll probably have to winnow out the music and other media you normally carry around on your 30 or 80 GB iPod.

Tunes will also sync your Mac or Yahoo Address Book contacts, calendar events from the Mac’s iCal or Microsoft Entourage or Outlook on a PC, email account settings, and Safari or Internet Explorer bookmarks.