Even the original closed source wherigo player is so bad that it's not very entertaining. A reverse-engeneered open source variant probably won't make it more fun.
Seriously, there isn't even a documentation of the cartridge format. So no, i don't plan to work on wherigos.

This is by far my most used and favorite N810 application.
Is there any chance it could get ported to other platforms such as Desktop linux/Windows, or even android?