That is a kind of a bullshit argument though isn't it, that "hey look, the interns (supposedly half-able, incompetent newbies) are getting paid so high!! We have such wonderful salaries in tech!"
It's a lie, a total misrepresentation of the facts. The interns are usually super programmers themselves. I mean, for instance, when Alex Gaynor was "interning" at Quora he ported Quora to run on PyPy. He's a really big contributor to projects like Django and PyPy. When he's "interning" at your company he's probably more able than a lot of other folk you could find, and he should be getting very big bucks. So this argument is really just complete hogwash. A good amount of times I see the interns training employees rather than the other way around (as it should be).
Secondly, they're interning in the valley, where "boarding" costs are about equal to costs of getting a mansion in a midwestern city in a reasonably safe and fun neighborhood. When you're "making 90k" in the valley you have the quality of life worth ~60k in a midwestern city. If anything, they are underpaid.
edit: minor revision on figures for clarity of argument; though I do agree with moc down below when he says "If you're comparing suburbs (Silicon Valley) to suburbs, the discrepancy is much greater and I'd say that $90k/CA ~= $40k/Midwest"