CNN has had a very good week, winning the 10 pm EDT hour from the Democrat Convention four nights in a row.  
Not just beating its cable competitors, but all the broadcast networks who have had news specials that hour as well.

These are the numbers for the Barack Obama speech Thursday night:

CNN (10-11) — 8.07M
ABC (10-11:07) — 6.58M (Lead-in: Grey's Anatomy — 4.01M
NBC (9:53-11:02) — 6.10M (Lead-in: NFL Games — 2.8M*)
CBS (10-11:03) — 4.72M (Lead-in: CSI — 5.30M)
FNC (10-11) — 4.22M
MSNBC (10-11) — 4.07M

Be interesting to see if CNN can repeat the dominance at the Republican Convention next week.

Looks like the non cable only networks carrying the speech affected Fox numbers as they are usually dominant.