Two updates from HackingRoomba.com.
First, if you’re unsure about how to get into hacking Roombas or just want some tips on how to get cheap Roombas, see the DIY Robotics with Roomba Holiday Buying Guide.
Second, if you’ve got a MacBook and a Roomba, try out this way of using the MacBook’s built-in tilt sensors and Perl to control your Roomba:
(revver link)
Full details available on the Hacking Roomba project page.