As far as I know, they pushed back the deadline for requiring a passport to enter the US from the Canadian border (I live within 45 minutes of the border, and pass through the Champlain border a few times a year).
The last time I came through, I had gone up to Montreal to see Radiohead, sometime in July. Coming back, the border guard asked to see our passports, and we responded that we didn't think it was currently required in order to gain entry in the states (none of us had one, only drivers licenses). The guard sarcastically responded, "Oh, well, maybe you've heard of this thing, its called 9/11." He then handed us a pamphlet detailing the border regulations, and questioned us for about 5 minutes before letting us past.
So, we were able to get back in sans passports, without too much difficulty. Funny thing is, I was reading the pamphlet as we were driving down the interstate back home, and it didn't say anything about a passport being required.