I just did a presentation [PDF] on carbon cap and trade. In it, I spoke in favor of carbon taxes and against cap and trade (for fear of the political manipulations that are all-too-likely).*
In particular, I highlighted the importance of taxing carbon as close to the source as possible, the necessity of rebating ALL tax revenue (or auction revenue, should C&T be enacted) to citizens, and the importance of allowing price signals (HIGHER PRICES) to work.
I did the presentation at the annual meeting of the National Association of [Investor-Owned] Water Companies [site]. NAWC is worried that carbon taxes/C&T will increase the cost of delivering water -- as it should -- and that revenue from taxes/C&T will be rebated to "favored" industries (e.g., municipally-owned water companies) -- as it should NOT.
When preparing the talk, I was surprised to learn that the EPA's SO2 auctions (the famously-successful ones that have been running since 1995) account for less than 3% of total SO2 permit activity. 97% of permits are given to industry -- and then traded.
Bottom Line: We should tax carbon like we tax gasoline: Taxes are simple, transparent and hard to manipulate. We should then rebate the the $billions (trillions?) in tax revenue to citizens, not "favored" industries.
* For more debate, see this