Rules are, if the friend invited you, and in many cases even if not, they are responsible for being overly friendly and inviting you over and introducing you to a couple of the people in the group. If it's a programmer/founder get together, then in the same sentence your friend should also include a major interest or skill or job you have.

Sadly, many technically minded people are not aware how to be good 'hosts'.

I wouldn't give up though. There aren't many programmer/founder organizations out there. Go again but arrive earlier, when people are just arriving, before the joining of the tight circles (loud bar?). Introduce yourself to the best groomed person you see and then, when your friend arrives, call him over an make sure he knows everyone. It's the right thing to do, and your friend might understand how helpful that can be.