Are you familiar with Timeshare (http://en.wikipedia.org/wiki/Timeshare)? It usually refers to property ownership, but can apply to pretty much anything. Most people consider the middlemen in timeshare situations to be scammers, so it would be tough to market.
A few problems:
1. The subject property breaks, who pays? Insurance is clearly necessary, but who will go through the time to process a claim? What if it breaks in transit between owners?
2. Theft. What's to keep an owner from disappearing with the item?
I have a similar concern with this. It's too easy for a scammer to just walk away with an object. Invest a small amount, run away with an object of far greater value.
There are communities who do do this. I wish I had actual references to point out, but stuff like only having one or two lawnmowers for a neighborhood does happen. It's a cultural thing more than a business opportunity.
OTOH, what if you looked at this from the perspective of a dating site? The goal isn't merely to collectively own a thing; it's to find and meet people who you could get to know well enough to trust and participate in collective ownership.
