Edmunds TMV is indeed based on what other people are paying for a make/model in your zip code.
I don't know why your local dealers are offering a price that's right at invoice. I guess they are hungry to sell cars.
The invoice price is what Honda ostensibly charges the dealer. But that's not the true cost of the car to the dealer. If the Accord just got to the lot (or is in transit to the dealer), then the dealer's financing costs (holdback) are minimal.
The dealer may still be trying to meet an October quota for a bonus (sometimes the months are "stretched" out for bonus purposes, but 5 days is a bit of a stretch). The dealer may have over-ordered a lot of Accords and needs to get rid of some before they all arrived. Or maybe if the dealer sells a lot of Accords this month, Honda will reward the owner with a cruise or other spiff. Maybe the dealers know the price trend for the Accord is down, so they are discounting early. Who knows.
There's one more factor, from How We Calculate New TMV Prices:
"When an all new or redesigned model is introduced, we display its estimated TMV® price, even though there may not have been any sales of that model. We do this because our visitors have expressly requested that we provide our "best estimate" of the transaction price as soon as the model is available for purchase. We update this TMV® price as soon as we start receiving statistically significant transaction data. "
I don't know when the '10s hit the lots, but the data may still be a bit sparse. But it's really not "all new" or even much changed for '10 is it?
Sounds like a great deal to jump on. Assuming Honda doesn't come out with any incentives to sweeten the deal, other than the current low APR. :-)
Enjoy the new ride!