Check it out, the Linux KingPin client has been released. You can read about the full deal in Ryan Feltrin's .plan update, here is the low down though:

At this time, it is limited to Linux glibc, and REQUIRES A 3D ACCELERATOR, which is compatible with Linux (most 3DFX and TNT/2 cards).Please sure to read the README file before attempting to contact me.Linux Kingpin v1.09beta - RPM Installation (recommended).(use 'rpm -i --nodeps kingpin-1.09beta_glibc-1.i386.rpm' to install with TNT/2 cards)Linux Kingpin v1.09beta - TAR Archive. Note: some non-Linux browsers are known to corrupt downloads of these files. Best use your Linux browser, and do a shift-click.

Also, GameSages has posted a "trick" which allows you to keep bashing heads in Kingpin, but on a Quake2 map. Here is a quick summary:

download a Quake II editor like quark or qped , load it up and open the pak1.pak in your baseq2 directory , open the maps folder and right click on the ones you want , choose export file and save the bsp in you kingpin/main/maps folder , if you don't have that folder make one, make sure you export the folder textures and place them in the kp texture directory