Another interesting part of the project name / url debate: Is having [product].com that important? In their book and blog 37Signals has generally played down the importance of urls. Pointing to the use of basecamphq.com for their project management offering. I must say I am on the fence. Clearly appending something to your product's name opens more options for un-squatted domains but at what cost to the end user?
I'd love to hear what people think about this. I think a .com name is important, but I can't back that up with any real evidence. And basecamp is a great example of it not mattering. We considered trelloapp.com (and use trelloapp on Twitter), and my guess is that it all would have turned out fine either way. But I still have a possibly irrational attachment to the [name].com
I know of a little anecdotal evidence: A .org I know of used to routinely have to remind people it was .org, not .com. The owner of another .org I know of once stated bluntly they "farked up" by not buying the .com version as well, which was bought at some point by a company (using the same name, if I recall correctly -- physically located elsewhere). And, of course, there is the infamous whitehouse .com to take advantage of the fact that even for .gov sites, people mentally default to the .com mode.
No formal studies or anything (that I know of), but there is some anecdotal evidence that it makes a difference of some sort.