[Griffinaz]

The phone is seperated into two different partitions for software on the internal drive. There is a music partition that is very large and there is an operating system partition that is very small. When the phone was designed it was not intended to store additional software on the OS partition. When a phone is jailbroken it opens the drive to installing new software. By default it saves the aftermarket software into the OS partition and after you have installed some large programs you will get a message that your running out of disk space even though you have a lot of room remaining. That means your running out of room in the OS partition.
The "fix" that is out there (several actually) will move your programs to the music partition and then create a link to the os partition. When you then install software it will think it is putting it in the os partition when it is actually saving it to the music side of the drive and you can then install basically 7 gigs or more of software before you start to run out of room.

As far as the instructions in the posting right above your first question, I have a program on my phone called Term-vt100. It is just a terminal emulator that allows commands to be typed on the phone in a "dos" like environment. The commands listed change the permissions and owner of the installer program back to the ones that they should be set to. In my case I installed a piece of software that changed the ownership of those and made it so they wouldnt launch. Typing those two command lines in the terminal changed those settings back.