http://elections.dailykos.com/weeklypolling/2012/9/7This represents no change from their last poll, which was also 50-44%, though they're polling LVs now (not sure if they were before.) Interestingly enough, the DKOS crew decided NOT to poll the week following the RNC. Interesting decision, eh?
Here are their one day surveys. You can see Obama drops from 51-43 on Friday after convention, to 49-45% two day slater on Sunday.
Friday 51 43 6
Saturday 50 45 5
Sunday 49 45 5
Edited to note party ID is D+7, 42%D/35%R/23%I