I was looking at some Survey USA polls today and noticed that in some of their polls they ask people if they've already voted and then break down those numbers.
Numbers for Georgia, North Carolina and Iowa below the fold...
Here are some numbers from recent Survey USA polls:
Georgia
(poll taken 9/28-29)
Already Voted = 9% of people polled
Among those who already voted:
Obama 64%
McCain 35%
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North Carolina
(10/5-6)
Already Voted = 5%
Obama 65%
McCain 31%
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Iowa
(10/8-9)
Already Voted = 14%
Obama 65%
McCain 31%
I realize these are just polls and not actual early voting numbers but this bodes well for the Obama campaign's ground game in these states, I think.