The limerain exploit has been patched so now they have to find a userland exploit that will give them root access and once they have that they are looking for low level exploits such as in the boot rom or a kernel exploit so that they can create a jailbreak that lasts. It involves a lot of code searching and poking around, and reverse engineering so it can take quite a long time. Pod2g was working on the shatter exploit for months before it came available. Once they find an exploit that works and is low level enough they then do the easy part and create a jailbreak using Apple's code to verify that it works. If that works they then have to figure out a way to get custom code for the jailbreak and then code how that is delivered to make the jailbreak work. A reason why we don't get in trouble from Apple for jailbreaking is that the jailbreak code is custom coded and does not use Apple's code or else we would all get in trouble for copyright infringement.
Originally Posted by K.J
I beg you and others to read the jailbreak wiki. Ignore the high level technical stuff but in doing so you will begin to understand how difficult of a process this is and appreciate it more. I know I did and after doing so tend to not have patience for those who scream for a jailbreak immediately and don't really like the timeframe to complete.