I own a 2006 HCH, and it just recently had issues with IMA and battery/other components. Mileage was 43,000, and we've always taken really good care of the car. The initial diagnostics took over a week for the dealer to complete. The first estimate of what was wrong was the Battery Control Module and the Motor Control Module, which would have cost over $6,000 to replace (a word of warning to you owners out there - once the car is past the warranty, Honda really doesn't do much to help you out, even if the car is just past the warranty period).
Of course, I had a fit about the cost

(and there were other issues regarding the service contract we purchased - Rosen Honda, Gurnee, IL, said it was "bumper-to-bumper" coverage, but when we made a claim on the contract policy, Advantage said there was a specific exclusion to hybrid parts - Rosen still claims to be unaware of the exclusion).
We got a new battery, which was still under warranty, but the problem was still there. Pauly Honda in Libertyville, IL, decided to try and get some special (and apparently difficult to get one's hands on) diagnostic equipment to narrow down the possibilities, instead of throwing parts at the problem (duh).
It turns out, a wire that connects the battery to the control module had become corroded after our car sustained some wind storm damage in March of 2007. Apparently, even though it wasn't raining at the time of the damage, there was a tiny amount of moisture that went into the battery compartment and corroded one wire.
This problem completely confounded the mechanics at Pauly Honda, but I have to say that I appreciate their perseverance in finding out the true problem, even if it meant that I had to go for 11 days without my beloved car

. I'm so happy to be able to drive my car again!
I think the mechanics at Pauly were in contact with Honda's Engineers, so hopefully they've documented this particular repair and are planning for a design change in future models. I would think that this may be a problem for others, as well, if even moist air can harm the components of the battery and control modules.