OP - Here is something you can use to your advantage. You normally have 45 days from the date you leave a job to elect COBRA coverage or not. And if you elect the coverage, it is retroactive to the date you left your previous employment. If in the first month you need medical coverage you will probably need to pay out of pocket or get them to bill you later, then after COBRA kicks in and processes the bill, you pay whatever is your normal out of pocket.
BUT - Say you go to the doctor and the bill would be $250. But your COBRA coverage for one month is $1000. It makes more sense to just pay the doctor yourself rather than pay COBRA. And the great thing for you is that you can wait until after 10/01/2008 to decide on COBRA - then decide if you "really" needed it for December after all. If yes, the pay for December’s COBRA and get the bills reimbursed, if no, then don’t worry about COBRA and carry on with your new coverage starting in January. And the 30 day gap with no coverage will not cause any issues with insurability either.