Arctic Sea Ice since 2007
Year . . . . Average Minimum Extent (million square kilometers)
2007 . . . . 4.28
2008 . . . . 4.67
2009 . . . . 5.10
Al Gore claimed during the Copenhagen Climate Summit that "These figures are fresh. This is the volume metric measure of the ice and some of the models suggest to Dr Maslowski that there is a 75 per cent chance that the entire north polar icea cap, during the summer months, could be completely ice-free within five to seven years." Gore apparently didn't have the last two years of data with his "fresh" figures. For the AP version of the story, which doesn't question his claims at all, see here.
The claim was simply obtained by extrapolating the drop from 2006 to 2007 and assuming that the rate of drop would continue. The fact that the amount of ice increased after that would presumably bring some caution to the discussion.