LTE is slowly being introduced but it won't be fully integrated nationwide for years. For example, it took almost 3-4 years for At&t to introduce 3G in my local area after the technology was first made available and there are still huge gaps nationwide lacking 3G nationwide. Even Sprint's new 4G network is only available in a few markets currently and they only sell 1 phone that supports it.
If you need or want a new phone now, get it.
I can't seem to find a straight answer on when Verizon's LTE network and LTE capable devices will be available. I've read it'll happen by the end of 2010, mid-2011, or even that nothing will be worth having until 2012.
I picked up my Droid X about 10 days ago and I'm starting to wonder if I should return it in the next 20 days so I don't have to wait too years to get on the super-speedy LTE wagon.