I got in with a gpa of 2.7 from undergrad, however, my situation was different. I have an Aerospace degree and worked 4 jobs to help pay for school....still partied and was in a fraternity too.
If you're serious and want to show them you've changed, first do what Otto said and read around. Secondly, have you taken the ASTB yet? If not, start studying your ass off to do well on that test. You may also enroll in some grad school classes to really show the board you're capable and serious. I had half my Masters done before entering the Navy, but had to stop due to being laid off and I wanted to get in the Navy. My grad school GPA was a 3.9....which definitely helped show the board what I was capable of doing.
Be proactive and better yourself. Go volunteer, get a teaching job, give back to the community. Contact a local recruiter and get some ideas. This process is about applying yourself, no one is going to do it for you. There are tons of things you can do and they are spread around this site, just search. I already gave you a few ideas....now its just about how badly you want it.
