For the record... McCain was leading on 9-16. That was only 3 weeks ago.
There are 4 weeks till the election so it is possible that McCain can still turn things around. It is almost certain that things will get tighter. Although I am not sure if McCain CAN pull off a victory.
I also think the most important number to look at in these polls is not the margin between the two, but the top number and whether it is over 50%. Despite McCain having the two worst weeks possible Obama is still barely getting to 50%. That implies that there is still a chance for McCain to climb back into the race, if he does it right.