The Tax Foundation may be a conservative outfit (they're the ones who bring you "Tax Freedom Day" every year), but they emailed to let me know that they produced a report of their own last year showing overall tax rates at various income levels. It shows that federal taxes are progressive, state taxes are about flat, and total taxes are modestly progressive. Basically, the tax rate for the average worker is 28% while the tax rate for the richest taxpayers is 34% (and probably a bit lower than that for the very richest taxpayers). That's not exactly a socialist hell.
Anyway, you can never have too many tax graphs, can you? I can't vouch for how accurate this one is (the methodology for this stuff is pretty tricky), but their numbers look like they're in the right ballpark to me. Just thought I'd pass it along.