Not familiar with US legislation. Does anyone have a guess whether this will move the price up or downwoards?
It's not going to move the price but its a pain in the ass for taxpayers to have to try and track every trade. It's probably impossible to do it with the current technology as this would have to be built into clients themselves to work.
Bitshares wont have this problem as much because of how it's designed but if you use Cryptsy it means you have to track every single trade and the capital gains on everything.
If you use all sorts of mining pools, Cryptsy and sites which are shut down or the information is just lost, you'll have to deal with the IRS someday unless we can get a law passed to make cryptocurrency tax free.
Technology doesn't solve every problem. Sometimes you have to work the system to get a favorable bill passed and that is the reason to interface with regulators.