To your point regarding the EUA and SLA, When I bought my iPod touch and when you bought yours, neither of us were given a copy of any "EUA" of "SLA" documents, and certainly, no signed agreement exists. Copyright laws exist which would prevent one from appropriating Apple's software, or changing any part of it, for personal use. You can, however, create other software which will work in conjunction with the Apple software. This is the basis for jailbreaking. There are thousands of existing webapps and native apps which have been developed (prior to the SDK) expressly for the iPohone and touch. I don't see Apple going after any of these developers for copyright infringement or softward piracy. None of these existing applications require any type of "Apple signature", whatever that is.
You can do anything you want to your iPod touch, you just can't modify the software, although you can add to it. For that matter, you could erase the programming all together and install Windows or Linux if you have the expertise to do so. It's no different from your home computer. You bought a computer with a pre-installed operating system. If you don't like the operating system, you can buy programs which enhance the operation of the computer. Or, you can remove the operating system and install another brand of operating system.