May your firmware is higher then 4.1 and so it doesn't work so downgrade your firmware
Yes, now Greenpois0n can jailbreak iOS 4.2.1.
No you do not put Greenpois0n on an iPod. You install Loader which in turns installs Cydia.
greenpois0n.com
greenpois0n is the best jailbreaker for ios 4.1 on windows that i have used( i have personally used it and it is safe , just beware of fake downloads)
No
Yes, GreenPosi0n is a free jailbreak for iPhone, iPad, and iPod Touch. You can find the link to GreenPois0n's offical site in 'Related Links' below.
It already is for a long time
Yes, but personal I think using greenpois0n is better (because I did), it is way easier, it also shows you instructions on what to do.
No it only works with 4.1 and other firmwares.There are not alot of 4.2.1 jail breaks yet.
it has but not for the iphone 4
Of course...by restoring the ipod.
It is a matter of opinion, in my opinion Greenpois0n is better because that is what i used to jailbrake my ipod touch 2nd generation 4.2.1 ... do NOT use jailbrakeme.com that is just a virus and it brakes your ipod.