For the MC model you can use Redsnow jailbreak
redsn0w is the alternate to greenpoison
u can use it for free download i t from the link given below!!
http://www.wikihow.com/Untethered-Jailbreak-4.2.1-for-iPod-Touch-2G-Mc-Model-With-Greenpois0n-RC6
ENJOY!!!

Apps compatable with Ipod 2g,ipod 1g,iphone 2g,iphone 3g
*ninja jump
*temple run
*fifa 2010
*cut the rope
*fruit ninja
*call of duty
*doodle jump
*cut fingers
*bike mania
*need for speed undercover
*snooker pro
*action ball
*paper toss
*lane spliter
*angry bird seasons and many more if want more keep visiting the blog!!
caution:-(jailbreak needed
*

Apple left his old devices in an dark room!!
they cant be updated upper thn 4.2.1
but know with the help of green poison u can jailbreak to get some good apps like facebook,temple run etc
know here we goes
1:-you need to find green poison ipa
2:-install in itunes
3:-crack with jailbreak
4:-reboot ur device
and its done
Thankyou regards:-nosherwan