This article wonders if the incompatability of most of the common iPod accessories will put existing iPod owners off from buy a new iPod. Here's my answer, anyway: Yes.

My iPod is well used, and I've purchased two accessories - the iTrip for playing music in the car with the kids, and the Nyko button relocator for listening by myself on a crowded commuter train. When the Nano came out, I figured the next thing would be a 20GB (or more) flash version, at which point I'd probably buy a second one so my wife would have one for driving around town with the kids while I'm at work.

Now, I have to deal with the following realities:

• The new 30GB model does not cost $299 as advertised. It costs $359, because I need to shell out $30 each for a new iTrip and button relocator (both of which are not yet available)
  
• When the iPod charge runs down, I typically recharge it while playing music (especially with the kids in the car who don't want to hear about "recharging" on a long trip without their music). Now that the devices will use the Dock connector, this won't be possible (unless they build a passthrough port). All of this besides the point that I'm not sure I see how you do a button relocator if you need to connect to the bottom of the device.
  
• Apple is now requiring a licensing fee from the people that make the peripherals (the article linked above says 10% of the wholesale price), so it's possible that the replacement devices will run me more than $30 each.

Seems the tempation to flex that monopoly muscle lives outside of Remond, WA after all...