Recruiters: get involved.
karmajunkie.com
karmajunkie.com
In fact, a couple developers from one of the companies attended frequently, and it was a few months into it that they found out I sent an email to their company. They found out about the group from different channels. Whoever received the email didn't even forward it on.
A month ago, I received a call from a recruiter asking if I knew anyone in the group with a specific skill set. They were hiring for another company that also ignored my email.
I'm only sponsoring the group because there aren't any running up here, and I enjoy helping grow a software community. When companies want to hire people, but don't take the initiative to meet potential candidates who are obviously interested in their work, they are neglecting a very obvious talent pool.