I endorse Brunno Silva's answer. Great stuff. Also -
You need to define what you mean by "qualified" or "top talent". And you need to tell us your expectations. Is this an overall capability thing? Or are you looking for perfect experience? Are you looking for very particular niche experience? Or have you defined your preferred candidate in terms of being exactly like the competitions' people? Or do you expect to optimize all of these factors?
Now for something that will make half the people reading LOL or sneer - hopefully not:
Perhaps you should court and be open to the invisible but large segment of unemployed or poorly employed IT workers. Especially the segment that is scorned by all hiring parties - the highly experienced, veteran (15 years+) IT worker.
The startup and social networking segments always appear to ignore the vast swaths of laid off, capable, senior IT people located outside major technology centers of the US. MIS, telecomm, and in some instances insurance and financial industry types are all hurting for work.
What exactly is the matter with finding a laid off client-server developer (yes, older stuff from 8-15 years ago) and working out a retraining deal?
"Past" technology experience commonly appears to be interpreted as a taint of badness by those immersed in new technology. That is an incorrect judgement that reflects ignorance.
Generally the current technology stacks used in the web and social media industry and by most startups are far simpler than the garbage that much of the senior technology crowd has dealt with in the past - such as Frankenstinian client/server and early web technologies.
Truly excellent past companies such as HP, DEC, and IBM in their primes hired for capability and character, and then trained for specifics. Today, the transition for someone to go from (say) Perl to Python or RoR appears trifling. (Anyone honest about it knows that this is the case.) Whereas a developer familiar only with current tech would strangle on older technology's quirks.
I did not even mention that someone who has seen a few fads come and go in their career will tend to be more flexible when the tech changes again.
Today companies expect perfect fit right out the chute. No wonder finding the "right" person by that criteria is virtually impossible.
The right person may have the "wrong" current resume, is what I am saying.