The numbers this month: Hillary 36%, Obama 25%, Edwards 14%. Last month, Hillary 41%-20% lead over Barack Obama, with John Edwards at 11%.
So it seems Ben Smith was right. Though, with Obama giving the best speech at the Iowa Jefferson-Jackson dinner, it seems the only way to move is up.
P.S. The second poll Marc Ambinder mentioned, from the Boston Globe, also shows progress, though not as much as Taegan Goddard said:
On the Democratic side, Hillary has 35%, Barack Obama 21%, and John Edwards 15%. This is in line with other polls that are now coming out, showing Hillary ahead but down from her previous highs in the 40’s.