Via Pollster.com, I see that Newsweek has just released a very encouraging poll for Obama. It shows him leading McCain 51-36 overall after being tied at 46 a month ago. Perhaps more encouragingly, Obama does better among Democrats (80-11) than McCain does among Republicans (78-12) and enjoys a substantial lead (69-18) among Clinton supporters. He also leads 48-36 among Independents, 45-43 among whites, 54-33 among women, and 44-41 among people 60 and over.
(The link to the May numbers doesn't seem to work, but the write-up of that poll says Obama trailed 40-52 among whites.)
It's all slightly too good to be believed, but the trend line is probably accurate, which has to worry the McCain camp.
P.S. In other poll news, the latest USA Today/Gallup poll is also out today and shows Obama with a 48-42 lead among registered voters and 50-44 lead among likely voters. The same poll in early June showed Obama up 49-44 among likely voters, casting doubt on my theory of bounce understatement. In my defense, the polls aren't entirely comparable, since this one has a much larger sample size (1310 v. 803) and therefore a much smaller margin of error. But that doesn't really get me off the hook.
--Noam Scheiber