That's the problem with the rbbb, gotta think about the programmer since it isn't built in. Well I have the "p4" pictured above, but it is serial port. There is a USB cable too but it is like $25. I actually use an iDuino as a usb programmer these days($18) but with a homemade adapter to utilize the p4 pinout for my existing creations.
More advanced options: You can slap together the parallel programmer (dig around arduino.cc). With a couple transistors you can build your own serial connection, see the lower left part of the serial arduino schematic:
http://webzone.k3.mah.se/k3dacu/ardu...o_rs232_v2.png
It wouldn't be so bad to build your mpguino around the rbbb and pick up an iduino for programming purposes (
iDuino - Breadboardable Arduino Clone -=- Spiffie.org) Then you will still have a duino to mess around with and an mpg gauge. But the P4 serial port interface is cheap if you have a serial port.