Extended Warranty on camera lenses

I'm not a warranty guy, but when I know a product is suspect to a high failure rate (cough)Xbox360(cough), I think it's a worthwhile investment.

I recently picked up the Canon 17-55mm 2.8 IS USM. And, although it does come with the 1 Year US Warranty, I'm wondering about years 2 and 3. Squaretrade is contacting me, trying to sell an extended warranty. This lens definitely has it's share of dust build up issues, and the IS has been known to go in a small percentage of these as well.

Would you recommend buying an extended warranty on this particular lens?

Wat does the extended warranty cost you? What would it cost you to clean the sensor or fix the IS if it breaks down? How intensive will the lens be put to use? Weigh the "probable costs" against the cost of the insurance, and you will have an answer.

Personally I wouldn't buy extended warranty for a lens, but if it makes you more comfortable with your equipment it might be a good investment.