new ipods won't work due to the elimination of the 30 pin connector.
the last of the 30 pin units may not work either, the cable supplies power via the firewire pins (9-15 volt) Apple eliminated firewire from their products, thus eliminating the charging capability from them. these units will only charge using the usb pins (5 volt only).
if you plug in your ipod and it says "charging not supported with this accessory"...well...charging isn't supported. the control will still work, it will just run off the battery. you will need an adapter to charge it.
copypasta from the instructions:
Some of these devices include the iPhone 3G & 3GS, iPhone 4 & 4S,
iPad, iPad 2, iPod Touch 2nd, 3rd, 4th, or newer generation and the
iPod Nano 4th, 5th, 6th, or newer generation.
These iPod models will generally display the message "Charging is
not supported with this accessory"
To fix this problem, you will need to insert a 12V to 5V charge
converter between the cable and iPod as shown here. These are
widely available on-line, at eBay, or you can purchase directly from us.
also, download manual here:
http://www.cdadapter.com/download/rc-ipod.pdf