My estimate, based on online research, that the agave's bloom spike would grow about a foot a week has proven pretty accurate.
Here it was two weeks ago, when I first discovered the bloom spike:
And last week:
And, once again, today:
And as an artsy close-up:
And, for kicks, looking like a palm tree (the same picture, but upside-down):
Although the blooming portends death for our beloved agave, I have learned that the bloom-and-die process could stretch out as long as a year. So, although I won't bore you with updates every other week, there should be plenty of time to document this miracle of the plant world.