I don't think so, but the closest thing to defragmenting is rebooting it I guess. Sorry, but I have no clue what I am talking about.
Why the hell would you need to do either of these? 1. Viruses on an iPod Touch? lolwut? 2. Defragging flash memory? lolwut?
Just to expand on why neither of these would be useful: 1) The iPhone platform is a sandboxed system. Even if somehow an app made it on to the App Store that did something malicious, it could only do something malicious to its own little sandbox. It can't get outside to access the rest of the system. 2) The primary reason you defrag a hard drive is because as files scatter themselves across the hard drive (fragment) loading them slows down because it takes time for the read heads to travel from one fragment to the next ("seek time") and defragging puts all the pieces in one place, thus speeding up the load times. Flash memory has no read heads, and therefore no seek times (or negligible seek times anyway) so defragmenting is pointless. It's also damaging, because flash memory only has so many write cycles in it before it dies completely. The less writing you to to the blocks of memory, the better. (Don't worry, you won't hit that limit during the normal course of using your device, but defragging will shorten its lifespan.)
