I know you are asking about ruby and python, but I don't think their strengths lie in interfacing with bluetooth, gps hardware devices, and running background jobs. You might want to look at some more industry standard languages.
I'm a Ruby advocate, but if "being like everyone else in industry" is one of your decision axes, Python is a more conventional choice for low-level programming (at least, outside of security).
The "industry standard language" choice you're alluding to is C, which is a terrible choice for a primary language in 2009.