Did you add any sort of additional peripherals to your machine recently? Third party RAM, firewire or USB devices, etc? Kernel panics are often very tied to hardware-- what sort of machine do you have?
The most telling information about the cause of a problem where a kernel panic occurs is that hideous spray of hexadecimal that comes up when the panic occurs, pretty much everything from the first line up to the "Waiting for remote debugger" line. Is it the same panic message every time?