As has been noted elsewhere the firmware for these devices has been a little strange, and Panasonic themselves don’t seem to have been quite prepared to support the phones in the field. Early adopters have had a difficult time obtaining support.
Perhaps the most useful info in the press release is the naming of the US distributors; Jenne Distributors, NETXUSA and D&H Distributing. If they are distributing the product then these folks should be able to point you to someone who can provide end user assistance.
As is always the case, when you buy something on Amazon because it’s really cheap you might not have access to the kind of support you ultimately require. This is especially true with new products. You may be better off paying a little more, but having a known reseller available to assist you should you need some help.
One new user over at the DSL Reports VoIP forum recently posted his experience getting the KX-TGP500 working with his local Asterisk server. It serves as a nice example for others going down that path. I know that the folks over at E4 have had them working along side Asterisk / Switchvox for a little while. They seem to be happy with the hardware.
I still have a KX-TGP550 sample here in my office, although lacking for a local Asterisk server I’ve not done much with it as yet. I tried to configure it with a couple of hosted PBX providers but ran into trouble. I suppose the logical thing to do would be to give them a try with a band new install of Nerd Vittles latest Incredible PBX.
There are just too many little projects like this to undertake, and not enough time in the day/week/month to get to everything.