Latest OC value comparison/review between i7 920 and Deneb :
http://www.pureoverclock.com/article809.html
Granted it's still not Lynnfield but the results should be close since they test the fixed OC frequency(3.9Ghz for both,both stock and i7 @ 4.5Ghz udner water-Deneb hit the wall @ 4.04GHz).Difference is not that big all around and SMT was ON in the tests.
Anyhow,what surprised me with Lynnfield is its die size of ~300mm2,which is actually a die size we would expect to see in MPU targeted at server market and not value desktop(750 model). The days of cheap MCM Yorkfields are gone for intel,now they fight value quad core segment with a much bigger die than 2xPenryn. This thing is faster than Yorkfield so people who considered value intel quad core will ditch aging s775 platform for the same priced s1156 platform(good for buyers ,bad for intel's margins).