You should have asked how hard it is to collaborate on the web. Well if you can get a team or just a few people to work with you and can menage to get something other than email for comuncation like free forums or such, than collaboration will persist as long as there is motivation.
Agreed the hardest part is finding people who say they will work on it, and actually do what they say. I've started several projects over the net with people I only know from the net. All of those projects died because people stop showing up to work on it.
I even joined a project some one else started, a few days later he wasn't heard from for 2 months.