This is a little too fishy.
March 18th (a Thursday night) the iPhone was found by a guy in the bar. That night, the person that found it viewed Gray Powell's Facebook account on the phone.
He's too drunk/tried/whatever to know it's not a 3GS until the morning, at which time the phone has been remotely wiped. If Apple could remotely wipe it, why didn't they try to locate it first? Maybe they tried. Why not push a message to it with contact info and remotely lock it? Maybe it was safer to render the unit useless.
The finder tries to contact Apple to return the iPhone-- but only calls Apple Customer Service. He didn't recall the name associated with the Facebook account he was browsing?
Two weeks later Gizmodo buys the iPhone. They photograph, disassemble (but not enough to show what CPU it's using, or any real juicy tech info).
Then Gizmodo contacts Gray Powell. How did Gizmodo know it was his? Why didn't the original finder contact Gray Powell? Gray Powell is a mid-level engineer. He's expendable. Everyone know Steve's temper. If he's blown the 10 million units/$100 million launch for the earth shattering iPhone 4G because he's been drinking... why does he still have a job a month after he lost the phone?
Apple sent Cease and Desist letters to the iPad scavenger hunt warning them that any publishing of photos and specs of the unreleased iPad would be considered a violation of their trade secrets. No Cease and Desist this time? The pictures are still up?
While I 100% believe the iPhone is real- there's a lot more to this story that we're missing. The skeptical side of me of me is thinking this is one elaborate viral marketing maneuver. You have to admit the 4G iPhone is at maximum hype level right now. This is the kind of pre-release buzz that companies die for. It's not normal Apple procedure-- but it's tactic in other's PR playbooks.
As someone who has found iPhones in the past and worked at getting them returned to the owner, the first place I would have looked is not Facebook but his contacts.
I highly doubt the story truly spans a month. The news would not have remained private for that long.
I don't, however, believe it to be viral marketing. That's too low-class for Apple.