I have friends who are extremely good engineers (i.e., a mix of: contributors to major open source projects used by a lot of SV startups, have given talks at large conferences, published papers at ACM conferences, great portfolio of side/student projects, have worked at great companies previously, frequently write high quality tech articles on their blog, have high reputations on sites like Stack Overflow, etc.) and who have been rejected at interviews from those same companies who say that they can't find talent. (it also certainly doesn't help that the standard answer is "we're sorry, we feel like there isn't a match right now" rather than something constructive. "No match" can mean anything on the spectrum that starts at "you're a terrible engineer and we don't want you" and ends at "one of our interviewers felt threatened by you because you're more knowledgeable so he veto'd you").
Seriously, if you're really desperate for engineering talent, I can give you contact info for a dozen or so of friends who are ready to work for you RIGHT NOW (provided your startup isn't an awful place with awful people, of course) and probably another dozen or two who would work for you given enough convincing.
I'm honestly starting to believe that it isn't hard to hire, but that there's some psychological effect at play that leads companies to make it harder on themselves out of misplaced pride or sense of elitism.
Unless everyone wants to hire Guido Van Rossum or Donald Knuth, but then a) statistically speaking, you're just setting yourself up for failure and b) you need to realize that those kind of people wouldn't want to do the glorified web dev/sys admin'ing that a lot of SV jobs are.