I'm actually not a bum nor do I live in Menlo Park.
However, I do live right next to Golden Gate Park and use it every day. I've also been lucky enough to have my apartment burglarized by someone who lives in the park so this article was of personal interest. I followed the comment thread on SFGate and found some links to this fellow's YouTube videos and his old blog:
Well, besides a bathroom, a laptop and some clothes i really don't need anything, i suppose that i could live like that. But in my area it's kid of dangerous after dark(gangs, dog packs, rapid climate changes). I guess we just over estimate the things that our civilization gives us, we don't actually need a lot of stuff, too much TV telling us what we need.
A friend of mine has been living in his van for the past five or six years when he's not on the road (he's a trucker). He's managed to save over $100K in that period.