In addition to Darkanubis74 post, there are some things I’d like to add and address. In his post, he referred to 3.55 and its hackability. In regards to this I have found several different sources of information and possibilities.
First, you must ensure that your console is hackable by checking the date on the console. Unlike the majority of consoles, model number is unreliable as they shipped the same models with various Firmware at certain points – there are 120 and 160gb PS3 that have the possibility to be hacked, so bear this in mind. Having said that, it is known that 3000 models cannot be downgraded, and some 2500 also cannot. To downgrade the PS3 however, it is only possible to do so via a hardmod – either E3 Flasher or Progskeet AND Teensy ++ USB.
It is possible to DualBoot on the PS3, meaning you can run 3.55 CFW (read below) and up to 4.20 OFW although I have no information on whether or not this works with 4.21, so be careful. For those of you interested in developing homebrew, it is also possible to DualBoot Linux and FreeBSD with the use of OtherOS++.
3.55 hosts a range of different custom Firmware available. For instance, there are: Waninkoko, Wutangrza and Geohot. All of which host different pro’s and con’s, so if you are planning to look into this, then I have one piece of advice; Read, Read, Read and Read! (Then again, the same always applies, does it not?)
A recent exploit that has hit the scene like a storm is the CEX to DEX exploit. This allows PS3 users of 3.55 and below to convert their PS3 from a retail console, to debug. There are a few benefits to this, which I shan’t go into. The main however; is that you can update your FW to the latest, and revert as you do so desire. There are drawbacks to this however, as one would imagine. For instance, it’s possible that Sony could patch this in the future (if it has not been done already), also from what I’ve sourced, you lose the ability to play Bluray and DVD. If you want more information then click *here*. Also, zadow28 has found a way to run PS3 games in full debugging mode, which is also a nice addition to this.
Finally, Deank has confirmed that a new custom Firmware is on the horizon known as “Red Power’s 4.21”. As the name suggests, it’ll be working with the latest Firmware, which is a very nice surprise. There is little information regarding this at present, but for those with consoles that are unable to be downgraded, you may, in the future have the ability to get in on all of this juicy goodness!