Holy crap!
Make sure that you check the suspension and alignment before you drive it again.

Finally got it fixed. Total Cost: $1360. Thank god for insurance. Replaced the wheel, tire, and Tire Pressure Sensor. Also had to get a 4-wheel alignment (duh), but no problems with the suspension or any other mechanical parts. The front air dam is still scratched so I'll have to see how insurance wants to take care of that.

Agreed, having the spare is a good idea for a number of reasons, but I don't think "IMS failure" is one of them. I find it hard to believe the Mazda IMS sealant would "come out of the puncture" if used as directed:

"IMS cannot be used in the following cases: The period of effective use for the Tire sealant has expired; the tear or puncture exceeds about 4mm; Damage has occurred to an area of the tire other than the road contact area; The vehicle has been driven with nearly no remaining air in the tire; the tire has come off the wheel hub; Damage to the wheel hub has occurred; The tire has two or more punctures."

Odds are, they neglected to follow all the IMS instructions and warnings. Maybe the puncture was a little too big (>4mm). Maybe it wasn't on the tread. Perhaps they didn't "start driving vehicle immediately so that the sealant can properly spread inside the tire" or "keep vehicle speed below 50mph". Also, after 10 minutes, you're supposed to stop and check tire pressure again.

One last thing, while my car was in the shop the "Curse of the Silver" hit me. Although it was a silver Dodge Stratus (4 cyl, absolutley terrible car, my '88 Volvo 240 MT was waaay better). Anyways, I was in Rocky Mountain National Park and I was turning around in a parking lot and stopped briefly to talk to the girl I was with (who flew from Texas to see me and was THRILLED about my new ride) then when I pulled forward I heard a metallic crunching sound and quickly stopped. Because of the sun glare I didn't see the trashcan and could only barely see it after I hit it. So I'm just waiting to see how much Enterprise is going to charge me for the paint I scraped off the plastic bumper. I should have driven it off a cliff, seriously, it sounded like it was going to explode at 4000 RPM, not exactly satisfying for an RX owner, or for a girl who thought she was going to be riding one.

yea, you might as well get the Spare Tire kit. The mounting bar goes across the rear suspension towers some what like a struct tower brace for the rear. You can think of it as a performance mod :)