Well ain't that some shit. 
I can't do anything without showering. I can't get dressed, I can't leave my apartment. . . which is why, unable to go back to sleep, I dragged myself into my bathroom at 8:30 this morning to get my hungover ass clean.

This is where I ran into a problem-- namely that, when I turned hot water handle, nothing happened. No water came out at all. Turning the cold water handle resulted in cold water, and lots of it. Another twist of the hot water handle and... nothing. I went to my sink, silently cursing at the apartment management for turning off the hot water without posting notices, and turned the hot water knob there, expecting nothing. Instead, I got a nice gush of hot water. So I went back to my shower, but damnit it wasn't going to give up hot water for anything!

I called the apartment manager's emergency pager. When she called me back, I explained the situation, and she said that she would have maintenance out shortly to unclog my showerhead. I tried to explain that the showerhead clearly wasn't clogged--it had cold water coming out of it-- the problem was that there was no hot water. She assured me that my showerhead was, in fact, clogged. I need a decent plumber. A real plumber who knows exactly what he is doing. 

The maintenance guy dicked around in my bathroom for all of 5 minutes, and came back out to the living room to report the following:

1. My showerhead was not, in fact, clogged.

2. What is clogged is the hot water pipe running to the shower.