Are you in one of the markets slated to launch with 4g? If so, waiting might be worth it. If not, a 3g phone now should last you until 4g comes.
A few things to consider:
1: If you sign a 1 year contract for the droid x, you can upgrade as early May 15th of next year (meaning that not only will more places have 4g, but there will be a slew of devices)
2: Verizon's gone on record saying that they're looking at tiered pricing for 4g, and they seemed to hint at a total rework of plans (you being able to buy data in bulk and use it on multiple devices) While this could be a boon if you are in 4g areas off the bat, it could mean paying more initially until 4g hits your area.
i am also of the opinion that 4g wont be too important to me. i always connect my phone to wi-fi when i am home, and as kyleg said, my 3g speed is just fine by me when i am out and about. faster is always better, but i can wait until next year (when i use my wife's upgrade to get the next big thing after the droid x, lol)
Nov or Dec of 2010? Really? I thought Verizon said their LTE network wouldn't be coming online until sometime in 2011? Wouldn't you wait until the network was up and running and beta tests done to release phones?