Well, strictly speaking, I suppose that the combination of Tor and Bitcoin is still a bit subversive from an anti-government perspective. But the problem is, obviously, not everything can be done in Bitcoin at the moment. And as long as we need to exchange between USD and BTC, this kind of thing is going to be a problem.

If BTC ever gains enough acceptance to (largely) eliminate the need to convert in and out of USD, it could be a real problem for governments who want to control all financial transactions.

Whether or not that will happen is anybody's guess. It's something of a chicken or egg problem, as BTC is less likely to gain mainstream acceptance if you can't easily convert to/from other currencies (USD probably being one of the more important ones). If BTC remains relegated to only black-market transactions on sites like The Silk Road... well... that makes it a bit less useful. :-(