I hate to say it, but they already have a "Made for iPhone" program where there are special chips the iDevices are looking for, and if they don't find it they will complain the accessory may not work properly:
Last I heard it never went past fear mongering but was still annoying. I can't remember if there was a way to disable it or not but I'm sure if so it was on by default.
That's nothing new. It's been around for a long time. I had a 2nd gen ipod touch. Apple wanted like $50 for their composite A/V cable (with the red/white/yellow connectors) so you could play video back on an old analog TV. Instead I went onto ebay and bought one for $3.50 that worked perfectly. Or at least it did work perfectly, until IOS 4.0 (I think that was the version, but maybe it was 3.0) was released. Then whenever the cable was connected, it would pop up that error message. You could still use the audio out on the cable, but the video portion was useless (I don't remember if it completely stopped working or was just useless because it showed the error message on your TV). The only way to get video out was to buy a new ridiculously priced official cable that had their DRM chip inside.