Am I the only one who hates how some projects are named like this?
The thing that struck me is that there are no one letter commands in UNIX (that I can remember off the top of my head). Not sure if there's any reason for this besides namespace scarcity -- only 26 one-letter commands you can have! It feels pretty arbitrary, I guess, to decide that Twitter is special enough that it gets to be one of the 26.
At one time, "f" was a link to "finger" on many machines, but I think that's mostly died out now.
And of course there's "X", although you usually don't run that yourself at the command line unless you're debugging something.