I've used an iPod Touch. It is cool if you need only multimedia and some games.

But Maemo beats it with (and I'm talking about end user characteristics only, things that normal people use and are used to, I'm not including the geeky stuff):

Videochat
Bittorrent
Expandable memory slots
Copy-paste text and images
Browser with flash and java
Browser password storing
Browse the device via bluetooth
Use any song as an alarm
True RSS reader
Video recording
A way to make apps wake up the device in the background
Stream live video (I'm not sure 100% you can't do it in an iPod, but almost sure you cannot play some formats)

All of these work on Maemo. Some might not be the greatest you have seen, but they work. And you cannot do them in an iPod.

I'm not saying the iPod Touch sucks, but it is more for the casual internet and multimedia user. The iPod is made as an entertainment gaget. The N800 and N810 are tools.