99% of the mentions of Atlas Shrugged I've seen use it as a target for mockery. Not just the "philosophy," but the writing style: it's practically a byword for turgid unreadability.
For a much longer (but, I think, insightful and amusing) variation on that theme, see http://bradhicks.livejournal.com/393124.html. Warning: not everything in the first paragraph is actually true.
The punchline of that joke is completely invalid: in the novel, the tycoons do in fact grow their own food. But then again, why bother to read an actual book when you can form your opinions based on hearsay?
BTW, here's my favorite comment on Atlas Shrugged, starring Bob the Angry Flower: http://www.angryflower.com/atlass.gif