the polaroid modules are great if you just want a self contained distance sensors
The modules have been in use in one form or another since the 1980's, perhaps even a bit further back, by a lot of robotics hobbyists. Polaroid used to sell a kit (basically the same as the SensComp kit; although I think the new kit may be a bit more efficient); hobbyists soon found how to mod the Polaroid camera modules.
The link you posted is a good one for that; some other good links are found on the Seattle Robotics Society site:
http://www.seattlerobotics.org/encoder/may97/sonar2.html
http://www.seattlerobotics.org/encoder/200010/dlcsonar.html
http://www.seattlerobotics.org/encoder/jul97/gensys.html
http://www.seattlerobotics.org/encoder/200008/daniel.html
http://www.seattlerobotics.org/encoder/apr97/sonar.html
http://www.seattlerobotics.org/encoder/nov99/Firstsonar.htm
http://www.seattlerobotics.org/encoder/200002/dougl.html
Recently, in Servo Magazine (July 2010, "Ask Mr. Roboto", page 13), Dennis Clark (who writes the column, and wrote the Seattle Robotics page at the second link, above) was asked how to interface the Polaroid sonar units to the Arduino - apparently it isn't as simple as what was already presented, so he wrote up for the column a new schematic to use with the Arduino, plus some code to get it to work (not sure how well this link will work, but here it is):
http://servo.texterity.com/servo/201007/?folio=13#pg13
Ultimately, the nice thing about the Polaroid camera sonars is that they have a good range, with a fairly narrow "beam" (15-30 degrees), which makes them ideal for "scanning" a room; even so, they do have drawbacks, but information at this link (referenced above):
http://www.seattlerobotics.org/encoder/may97/sonar2.html
...gives some info on how to further narrow the beam, and make it more "accurate"...
For the price (if you can pick one of the cameras up cheap at a thrift store or yard sale), and you don't mind spending time to mod it - it's a pretty good deal.
