2006 Update
Since this question seems to come up about once a year, I'd like to give the current answer. I was just on the Caribou Pond Road (a.k.a. Caribou Valley Road) this past weekend, and up to the famed metal bridge that first section was it's usual bumpy self, but still quite driveable (low cars might just have to watch out for one rock or two, and the usual bevy of pot holes). However, for that first rise coming off of the metal bridge, it was more eroded with deeper water-created ruts than what I saw last Memorial Day Weekend. Cars might still be able to make it through this, but you would have to be really really careful. What I found to be even worse was the first bridge after the metal bridge. On its northern side part of the road was eroded and washed out, creating a noticeable hole in front of the bridge. Thankfully I was riding with someone with a truck, but even so, we had to fill the hole as best we could with rocks and parts of trees in order to drive onto the bridge. I certainly wouldn't trust our handiwork past our use of the bridge, so please make sure you know what you're driving on before getting onto this bridge. But, please note, the bridge itself is fine, but it's only the northern approach in getting onto it that's tricky. Once past this bridge, there were just one or two rough spots (but nothing a carefully driven car couldn't handle) en route to the AT crossing, and the road was a little rougher on the way to the trail head for Redington (we encounted a small sink hole or two that we had to navigate around).
Just overall, the Caribou Pond Road past the metal bridge was in the worst shape I've ever seen it. In '04 and '05 I was able to (very carefully) drive my subcompact all the way to the trail head for Redington, but due mostly to the bridge after the metal bridge I wouldn't want to drive it in my car this year. I don't know if that section of the road is slated for repairs in the foreseeable future, but in a worst case scenario, supposedly the metal bridge is only a half mile from the AT junction, and it's just a little over a mile past that to the trail head for Redington. In my experience, on really rough roads it is often as quick to walk them as drive them in my car, and at least the former doesn't imperil my vehicle.
