I was on a business trip in Arizona over the weekend, and took a nice walk with a friend who was there for the same meeting. We ran across this very large plant, which she aptly described as a “giant asparagus”. We don’t know what it is, but it was fascinating – especially when we came across another that was starting the blooming phase… (if you know what this is, please educate us in the comments!)
EDITED 8 April 2014: turns out this is a “century plant” (Agave americana) but they don’t take 100 years to bloom. They do take 10 or more years to bloom, and they only do it once – and then they die! So we were quite fortunate to have seen two at one time.

I swear this is a real succulent – and it was super tall (that’s why it takes two photos to show it).