My 2003 5-speed HCH IMA light came on at around 83,000 miles - early 2008, 40,000 miles ago. The dealer told me at that time I should replace my battery, but it was still charging. I was driving to work 100 miles one way into the mountains, and couldn't do without it. Figured I'd drive it til it dropped. It still charges and discharges, and the light is still on. (The only other problems I've encountered with it were winters 2003 and 2004, when it was new. It had to go in three different times because under the (truly) coldest of mornings, it would not crank or make an attempt, although it clearly had juice - and the IMA light was on. The dealer performed electronic upgrades the two latter times. The first time, they still didn't have a clue, but it worked OK 2-3 days later when the weather improved.)
Reading entries above, I guess I need to take it back to the dealer again and see if maybe I'm running a risk of it getting a heat injury, or worse. I had given up on them when they told me to get a new battery. Thanks for the heads up. I'd buy another 5-speed HCH, used or otherwise.