Ok getting the ball rolling here a bit:

Governments might not have an issue with bitcoins' "anonymity" - it's fleeting. Consider the richest BitCoin holders - with basic traffic analysis on networks, it would be relatively easy to track one bitcoin address and related transactions - and map them to IPs and IPs of people sending them coins.

This would produce the ultimate in tracing financial transactions. This kind of information would be very powerful, especially in watching for large events, such as large corporations finalizing a deal - a big transfer goes through - this would mess with stock markets (but in a perfect world, the market will build this into the price immediately, along with a speculative value for the timing of the transaction before it actually occurs).

Would this not be a boon to government surveillance, far beyond what is capable now? Psuedonymity can be useful, but once its traced to a particular individual, all future transactions can be tracked against them. And merely generating more addresses isnt always possible - you'll want your contacts to know your current BTC address to pay you and not have to go find another.

Perhaps a crypto network escrow service that hides actual addresses, without needing to give a central entity full control of your keys is possible - another p2p identity verification network?

This ability to track and trace all trends and transfers of money will allow for some amazing economic and financial manipulation by large players -- unless the system already prices such risks into itself inherently by its own nature. Perhaps untraceable cash and imperfect knowledge, in a currency with imperfect liquidity is required -- is BTC actually the libertarian's nightmare disguised?