Here is the Deal.
The 1090t WILL bottleneck the 7970 in some cases. The main ones of concern would be Elder Scrolls: Skyrim and Battlefield 3 (Multiplayer). Both these games are fairly poorly optimised for CPU performance and only fully use 2 or 3 threads, as a result the lower single threaded performance of the 1090t will cause the bottleneck.
In comparison the i3 2100 has excellent Single threaded performance, and although it only has 2/4 Cores/Threads, games that are out these days barely utilise that fully (Although 4 - 6 threaded games are becoming more common). As a result the i3 2100 performs better than the 1090t.
Bare in mind that an i5 2300/2400/2500/2500k will outperform a 1090t in all cases including the heavily threaded applications due to the fact that its single threaded is higher even than that of the i3 AND it has twice as many cores.
Unfortunatly this leaves AMD without a recommendable CPU at any price point - the Sandy Bridge CPU Architecture is simply too strong - Even the Dual Core Pentiums are going head-to-head with the Phenom II 955 and keeping up.
And most people forget this little comparison but Intels Single Core Celeron G540 @ 2.5Ghz is much faster than its price point counterpart the Athlon II 250 Dual Core @ 3.0Ghz.
http://www.xbitlabs.com/articles/cpu/display/celeron-g540-g440_6.html#sect0
This helps prove the point that single threaded performance still matters and Sandy Bridge has LOTS of it.
TL: DR - 1090t will be a bottleneck in some games, in Skyrim and BF3 you will notice FPS spikes and/or lower than 30fps gameplay in certain cases.