Bootloaders

Looks like you can get away with using the FT232RL..

Serial via XBee radio modules: http://ladyada.net/make/xbee/arduino.html

Bully Bootloader: http://www.google.co.nz/search?hl=en&q=bully+bootloader&meta=

18F Bootloader: http://forum.microchip.com/tm.aspx?m=358348

The reboot server is used to reset the pic and allow entry into the boot loader without having to press reset on the device. This is handy for remote updates. The reboot server is only a small part of the boot loader.

The PIC is programed by uploading the .hex file to the device using FTP.

Have a good read of the user manual found within the stack installation directory. It provides an overview of the boot loader
\Microchip Solutions\Microchip\TCPIP Stack\Documents

Tiny bootloader

http://www.etc.ugal.ro/cchiculita/software/picbootloader.htm