The last time I checked into it, the 4yr degree thing was mandatory, but that was a few years back.
Tried the FBI, CIA, and NSA, the NSA was the only one I ended up in much of a conversation with, but while they liked my resume on paper, they said there wasn't any way around not having a 4yr degree unless you were specially recruited. I'm definately not that special.
My uncle works at Homeland Security and wanted to bring me in, but same problem with the degree thing.
I suppose I could always go spend a bunch of money and get loans to go finish school, so I could have a shot at getting into an agency and take a 10k/yr or so pay cut. But then again, maybe not.
And now that I mentioned every agency, say hi to the spooks reading the thread.