I think it depends on where you live. In the rust-belt I would probably go for it. I like doing all my own maitenance, repairs, and mods on my vehicles. What I don't like doing is fighting with a rusty stubborn bolt for hours only to break it or the part I am working on only to find myself in a bigger pickle than before. Thats where those extended warranties are nice. Let the dealer deal with that rusted or seized bolt.
That being said, I opted not to get the extended warranty for my '08 SR5. The only thing I took it in for under the original warrenty was the factory radio display quit working. Minor, but I felt it shouldn't happen. I could've replaced it with a "good" aftermarket deck but I was short on time. It will be replaced before long.
On a side note, when I bought my '04 silverado I got the extended warranty. Right away the front axle shaft seal went out. I took it to the dealer under the factory warranty. Their tech found a way to struggle with it and ended up ruining the whole front diff. 3 weeks and 3 rental vehicles later I had my truck back. Funny thing is, at the same time I had an older silverado that the very same seal went out. I rebuilt the whole front diff. in my driveway in a day. At 50k miles the water pump gaskets failed on the '04. I called the dealer so I could use my extended warranty. They told me it would be about 2weeks before they could look at it. I laughed at them, went down to the parts store, got the gaskets and later that night had it back together. Next day went on a 800 mile trip with it.