Flash with sd card

I'm new to AVRs, but I love them so far... I was thinking about writing a bootloader that would look look for a binary image on an SD/MMC card on boot. If it was there, then flash the AVR from it. It seems this would be handy for in-field upgrades, it would also be extremely fast.....etc, etc. My question is: Has anyone already done an open-source implementation of this idea for the ATMega 2560

I have this hardware board One-stop Online Shop For Smart Home, HMI Display, Airspy, Diy Kits l ITEAD STUDIO

See this:
http://forum.arduino.cc/index.php/topic,16812.0.html

And tghe source code here:
https://code.google.com/p/rogue-code/source/browse/Arduino/bootloaders/RogueSDBoot/trunk

Also Nick Gammon's implementation: