I gave a brief talk today at the kickoff of DevFest 2012 at Columbia, and everyone was excited and still trying to figure out how to split off into teams. And I overheard a couple of conversations where people were trying to decide whether to join up with a group, where they might be able to tackle a more ambitious project, or to work on their own, where they'd have more control, ownership, and credit for the finished project. That's an interesting discussion to have, but it's not remotely the relevant tradeoff here. You always want to work with a team, preferably with people you don't even know that well, because you will expand your technical network.
Technical people don't like "networking", which feels a lot like pretending to be nice to people so you can ask them for favors later. We don't like pretending to be nice, we think personal favors interfere with meritocracy, and we like to think that we won't be in a position to need any favors. And I think all of that is valid. The great thing about working on a hackathon team with new people is you don't have to be fake-nice, you just have to work together. You can appreciate each other for your skills and what you've made, not how good either of you is at polite conversation. That's a much higher signal than networking-event chatter. On the value of networking generally, it's short sighted to think of it as only for asking for favors. One of the most powerful things you can do with an extensive technical network is recruit them. In fact, the more successful you are, the more value you will get from knowing lots of talented engineers. A job-seeker can only get one job at a friend's company, but if your job (or better, the company you founded) is doing great, you can get as many excellent co-workers (or co-founders) as you know. Always work in a team.