The library is in the very early phases and the APIs are still under development but the README should point you in the right direction. Feel free to file github issues for features you would like to see and any problems you encounter.
There is also a command line order entry utility (currently for bitfloor only, but it will work for mtgox soon). The command line utility allows basic order entry commands without needing a web interface. The idea is for it to aid in testing when you are developing your trading bot.