A123 2200mAh pack!!!
 

I bought the new RC Driver magazine and the article on the Tamiya TA-05 IFS they show a A123 2200mAh pack. The funny thing is that it doesn't say anything in A123's website. I also looked in Horizon's website and same story there. One other thing, the TA-05 IFS has a very interesting looking front suspension system.

Good find, I just rechecked and it is a cool looking piece. It almost looks like they went with a flat cell

It sure looks like a prismatic type cell. The only problem, there is no info on them anywhere.

Could it be one of the A123 packs that Maxamps assembles and re-sells?

The pack in the Tamiya doesn't look like the normal A123 packs. This pack seems much thiner then the usual A123 packs.

Those are 2300mah, I think it looks like a flat cell or an 1100 cell in 2P

I haven't seen the RCDriver article yet - however:
I had an opportunity to use one of those packs a couple months ago in my Associated B4 buggy for local club racing.
It was a 2s2p 1100mah A123 battery pack the same length and width of a normal 6-cell nimh stick pack, and just a little bit shorter. That means it'll fit just about any place you can fit a 6-cell nimh stick pack.
It worked great for the 4 weeks or so that I used it, which included about 20 cycles.

A123 was not ready to release them mainly because their Hypersonic Charger beats the heck out of them when fast charging at 8-10Amps, which shortens battery life. They definitely didn't want to release a battery that would have shortened life from using their own charger. If they are showing the pack in a magazine, maybe they have a solution to the charging issue. I certainly hope so - I really want to use the pack in my race vehicles :)

Did A123 let you take pictures or they made you sign a form that wouldn't allow you to do it? How long did one charged pack last in race conditions? What is the discharge rate of the pack? There are a few chargers in the market right now that are capable of charging A123 cells.