I've been staying away from TV threads as I fear the mass threads of "What TV should I buy" and answers of "My Vizio looks better than any other TV I've seen!" However, there is major truth to the "Wait until January" argument. There's a lot of reasons and I'll try to go through them and their various reasonings.
First of all, prices for TVs when graphed form an asymptote, similar to the graph below:

Forget what the graph is about, just look at the data plots. See how the price starts really high, drops quickly , levels out and then slowly hits close to zero? Well that's how TVs and other big ticket electronic items are priced. You can buy a brand new Mitsubishi 65" LaserVue tv right now for about $7k shipped. Image that as the top price. Now, a year from now, the price might be $5k. Then two years from now, it'll be $2k and it's still a good TV. However, five years from now, that same TV should be close to $1k. There's a big difference between spending "close to" $1k and "close to" $2k. Just a primer in terms of spending and also part of the reason I'm so much against Vizio's and other extreme low-end technology marketers. Their products are literally obsolete and approaching the x-axis ($0 value) the second you walk out of the store.
Secondly, everyone knows the economy sucks. Even Joe the Plumber knows. Real disposable personal income decreased ~9% in Q3 after posting an ~11% drop in Q2 year over last. Consumer spending overall dropped ~3% year over last as well. The inventory systems of stores has been tightened up greatly over the past five years to follow JIT delivery. However, this year it's widely expected that Christmas will not be a big-ticket item holiday. Look at the retailers: Circuit City, closing stores. Best Buy, cutting sales and profit forecasts. Fry's, stopping plans to expand its' territory. Who's doing well? Wal-mart, $1 stores, Big Lots and other cheap retailers. Consumers are just not buying big-ticket items at this time in our economy; sales are down on big-ticket electronics about 20% year over last.
The final reason is there are new rollouts of technology coming in March of next year and the retailers need to get rid of inventories. When they are introducing new TVs and other high end electronics, retailers need to cut prices on the old products in order to avoid excessive lame duck inventory (slow moving). If they don't cut prices on the "old" models, when everyone knows the new models are coming out, no one will by the old models and they'll end up with massive stocks of product. So, I'm expecting a compounding effect:
* Decrease in demand for big ticket items
* Decrease in price to close out the old inventory
* Decrease in demand due to tightening of credit markets
If you have cash to pay for your TV, wait until after Christmas and look to spend around $1700-2000 on a TV. You'll get a great deal on a TV you'll be happy with for at least 5 years. For a frame of reference, the average life of a TV in the United States in 2001 was 9 years. Now, it's closer to 7.5 years. If you take out the outliers, especially the high end of people who just don't care about what their TV looks like and aren't in the market for high end TVs anyways, 5 years is well more than what you should expect to enjoy from a quality high end TV.
Sorry for babbling and not actually talking about anything technical.