I only got into podcasting a couple of months ago and have been downloading anything and everything that looks interesting. Inevitably I discovered TRGS, found it to be the most consistently funny thing I've ever heard (with David Mitchell's Soapbox a close second) and have since been downloading everything I can find and listensing to it repeatedly, so I can attest that even by half-way through Season 1 of TRGS, Gervais was saying they may as well re-name it to TKPS, as everything seemed to be revolving around him. As fans will no doubt know, it all goes back to their XFM days, where Karl was arguably the main draw by the time that came to an end. As Digital Sid says, Gervais used his name when what was essentially still the old XFM show went to podcast as no-one outside their relatively tiny audience had probably heard of KP.
Incidentally, if you're a Pilki01 fan (and who isn't), you should, ahem, search the internet, where you can get pretty much everything that G, M and P did, even the early XFM stuff.