In terms of direct company-to-developer advertising, Twitter seems to be very popular these days, and to a lesser extent local programming language groups/maili

In terms of direct company-to-developer advertising, Twitter seems to be very popular these days, and to a lesser extent local programming language groups/mailing-lists. Recruitment based upon github activity seems to be popular among startups as well. I'm currently working on a UK based startup that should hopefully make direct company-to-developer hiring easier for both parties (in the US you have StackOverflow's Careers site, but there's nothing really comparable for Europe).