Pusher is RiPDev's 2.2 version of a jailbreak. This should be avoided and not used. Instead use the dev team's jailbreaks. RiPDev's version will block access to / partition and make it impossible to install Cydia. (They want you using Installer of course). It's pretty much worthless since most the packages are in Cydia. The dev team's jailbreak allows you to use both Cydia and Installer. There is no valid reason to use Pusher instead of one of the pwnages below.
Update: This point had to be made. Pusher tries to say it doesn't void your warranty indicating that it is different than pwnage / quickpwn in this regard. It is not. This is a lie! Your warranty is officially voided, although a simple restore in iTunes undoes any jailbreak and you can always get warranty service. Using pusher or pwnage makes no difference in this regard.
Pusher is not better for newbies. The purpose of jailbreaking is to get as much non-appstore software onto your device as you can. Installer only offers about 8% of what is in Cydia. Certainly having 8% of the software packages is not good for newbies.