Nope. Nothing so ambitious. All you have to do is:
1. Ride it around.
2. Blog about it once every 5-7 days or so.

There may be some criteria, though. So here's some background on Adam Bruce, the guy who was lucky and industrious enough to somehow land this long term loaner:
1. Owned a Honda CBR-600RR sportbike
2. Founded streetfire.net, a community site for car and street racing enthusiasts
3. Has a car and sportbike-oriented blog
4. Runs a company that does auto and racing-related media production and product placement
I have nothing against Adam Bruce* and none of this is intended as a criticism of him or his blog. Dude got a free Super and, well,, good for him. I'll confess right up front that some of my stupefaction here comes from the fact that I didn't try something like this myself.
What I don't get is why Piaggio gave him a long term loaner so he could do what many of us do every day: ride our scoots then write about it either here or on our own sites.
I'm sure part of Adam's appeal as a recipient is that he's not plugged in to the scooter community but has connections to other motoring enthusiasts. That's great, but I have the feeling none of them are reading the blog and probably don't know about it. I found out about it via Vespa USA's Twitter and Facebook. But Adam hasn't posted anything about it to his own MySpace or LinkedIn pages. He has mentioned it on his Twitter, but hasn't ever mentioned or linked to the blog. If Piaggio USA is hoping he will expose his network to the joys of scootering, it's not happening yet. (No, I'm not cyberstalking the guy. He links to all of these on one of his "about me" pages.)
The blog itself is called"Scoot'n LA: Discovering Freedom on 2-wheels." Oddly enough, it's hosted on a subdomain of his company at scooter.autostream.com. So far, only the four most recent posts of 10 total are about the Vespa, comprising: 1. Gear up when you let friends ride your free Vespa; 2. Cameras and mounts (good post); 3. Riding up to Long Beach; 4. Got a long-term Vespa.
I have no complaints about the content (decent writing, good photos, uses clean and image-heavy "Autofocus" WP blog template), but don't really understand how it serves Vespa or warrants a long-term loaner. There's very little about reactions to riding the 300, the joy of riding, comparison to the sportbike. There are no mediations on "discovering freedom."
So, my quibble: Is that really all you have to do? If so, where do I sign up? The anonymous person behind VespaUSA's Twitter account just sort of chuckled when I asked them that. (No, seriously, I'll write a freakin' book about it if you want.)
*Nothing against Adam Bruce except this: I have left three comments on the blog in the past week and all are "awaiting moderation." One was an invite to join the LA, SD and Long Beach meetup groups. If you're reading this Adam, come on out. Let's ride. It'll give you something to blog about.