Specifically relating to serverfault:

As has been mentioned, reach out to some members (and non-members) who have well read blogs. Matt Simmons is an obvious candidate; Tom Limoncelli is someone else who's generic 'sysadmin' blogs I read.

Now on to an issue that may be hindering serverfault; not sure how to address it, but you should be aware of it. The term 'sysadmin' covers a far wider variety of disciplines than does 'programmer'; and the relative breadth and depth of knowledge varies widely between the <10 user office admin to the 3rd line network engineer at AT&T (for example).

From my observation at work (more on the 'enterprise' side of the scale) most infrastructure departments tend to be pretty siloed, particularly as the size of the organisation increases. You have your network geeks, your storage geeks, your database geeks, your *NIX geeks... the list goes on. Each of these groups probably frequent a different set of forums and blogs, with little overlap. You may have better luck trying to engage each of these communities separately? There are several excellent 'jack of all trades' on serverfault already; is it worth now trying to court the specialists?