According to their website: The IB Flat rate = $0.85. TF Nybot exchange fee = $1.14. So that's $2. Interesting that their website was all splashy recently about lowering futures costs.
The exchange raised their fees, not IB: https://www.theice.com/publicdocs/futures_us/Exchange_and_Clearing_Fees.pdf (from July 20, 2010 notice, pg 3)
Looks like the fee according to ICE's recent cost schedule was 94 cents for member firms. Their website PDF under the TF page still shows .94 as the rate. There is your 20 cent increase. Hmmm why so sneaky with this rate change? This makes TF somewhat less competitive to ES for sure. I thought the idea is reduce costs to drive up volume not the other way around!