I recently set up a JBL On Stage Micro speaker device with an old iPod for Tristan so he can listen to music when he goes to sleep and can wake up to music at the ungodly hour of 5:50 AM on weekdays. (He's 8 years old, wants control over when he wakes up, and his school bus comes at 7:00 AM sharp.) It was a frustrating experience, marred by confusing instructions (are batteries necessary even if you plug it into the wall?), difficulty finding four AAA batteries, an adapter that didn't fit a second-generation iPod nano, and an iPod with disk corruption issues.
All that fuss was preceded (and in essence caused) by the fact that although the JBL On Stage Micro states very clearly that it is "compatible with all docking versions of the iPod," it very obviously was not compatible with our oldest one, a 20 GB third-generation (3G) iPod. Although the iPod would play through the On Stage Micro, whenever it was docked, the controls became entirely unresponsive. Grrr...
That caused me to think that batteries were perhaps necessary and precipitated the whole-house search for four AAA batteries that I eventually cannibalized from our unused TV remote control. When the problem continued even with batteries installed, I tried the next handiest iPod, a second-generation iPod nano, which worked fine, but wouldn't fit into the provided adapter. Then I had to fall back to an iPod photo that Tonya had completely wiped while editing the next version of "Take Control of Your iPod: Beyond the Music," and it needed to be plugged into the wall to restart, after which it needed to sync, during which time it complained about disk corruption.
I mentioned this experience toward the end of a recent MacNotables podcast, and a listener wrote in to say that the problem with 3G iPods is a bit more widespread, noting an incompatibility between the 3G iPod and the iHome iH5 clock radio. That product claims to be compatible with 3G iPods too, even more specifically than the On Stage Micro's "all docking iPods." A customer comment on Amazon.com's listing for the Memorex Mi4004 iWake Clock Radio for iPod makes the same criticism - that the specs claimed compatibility with all docking iPods but his 3G iPod didn't work. And then John Faughnan pointed me to a post he made about incompatibilities with the JBL Time Machine Alarm Clock.
I suspect these problems are cropping up because there's a single supplier whose mediocre firmware is used by all these devices. Regardless, the moral of the story for iPod users in general, and people with 3G iPods in particular, is to beware of compatibility claims and to make sure that any dock-based speaker system that turns out to be incompatible can be returned easily.