Companies: allow your employees to freely work on open-source and it will improve your recruiting.
Apple barely lets their employees blog even, and last I checked they're doing OK by all counts.
Unfortunately, the intersection for people who are passionate about their 9to5 work and those that are passionate about their side-project seems to actually be fairly small.
So I agree with you in the case of Apple. But let's dissect for a minute why this is the case.
Apple can be incredibly secretive and still hire with no problems because
1) they are literally creating world-changing products and people want to be involved with that
2) they have a reputation for hiring extremely bright people. If you take a job at Apple you will interact with them (/ be one of them)
But outside of the big technology names (msft, google, fb, etc.) there's a huge collection of companies where either a) the brand is known but the company isn't know for being an innovative place in the hacker community or b) the company isn't known and neither is the team.
In both of type (a) and (b) companies you hear a lot of moaning from managers right now about how they can't find any good folks to hire.
So I'll qualify my advice a little bit: If you find you're having a hard time finding "rockstar-ninja-l88t programmers" by posting to Monster.com, maybe consider that you're approaching hiring in the wrong way.
Apple barely lets their employees blog even, and last I checked they're doing OK by all counts.
Unfortunately, the intersection for people who are passionate about their 9to5 work and those that are passionate about their side-project seems to actually be fairly small.