you can plug arduino via usb to a computer/laptop to use the computer/laptop for the main programm logic, using arduino only as sensor&actuator…

but powering an laptop all time..

hmm.. is there anything out there, using Python directly on the arduino?

you could use a cellphone/handy with symbian S60 and nokias DeveloperKit

arduino + Symbian S60
http://www.developer.nokia.com/Community/Wiki/Communicating_with_Arduino

or something more like this, python on a chip
arduino + py-on-a-chip
http://code.google.com/p/python-on-a-chip/
https://xcore.com/projects/python-chip

so i am waiting for a extra ArduinoPythonShield, in the plug and play way…
that would be great.. solving many starting problems with C/C++
having more fun, faster results..