I ignored the meowing for a while, and then, after several minutes, I gave in and went looking. Turns out, he was at the back door, and as soon as I opened the door, he sauntered in, just as though he knew the place, and us, and had just been waiting for us to let him in, which, I suppose is the case, at least in part.
He was a very beautiful, sleek, short-haired, glossy black cat, with white feet, and a tuxedo-like white splotch on his chest. He was very affectionate, and interested in exploring the place. JP was nervous, at first, about letting in a stray, but this cat smelled of shampoo and was obviously well cared-for, and familiar with people, so I figured it'd be okay, and JP was willing to go with my call on it. So the cat checks the place out, gets lots of scritches, snuggles into my lap for a bit, etc. When I tried to put him out, he was having none of it.
Somewhere in here, of course, I started to ponder the idea of keeping him. He was very, very nice and there was something about having him pop in and act like he belonged there that I found very convincing. He had no tags or collar. JP, in a move that fully solidified him in my mind as a Good Roommate, told me that I should just bow to the inevitable and take the cat to bed with me, because, as he said, "You know you're going to do it, so why fight it?"
And, in fact, if I were going to be home for the next several days/nights, I think I would have done it, because there was something that felt kinda fated about the whole thing. But the fact is that I can't really take in a mysterycat and then promptly leave for a week and ask my roommates (one of whom is allergic to cats!) to adjust the cat to our apartment. And, also, I don't believe in fate. So, I opened the door again and put the cat near it, and when he slipped out to explore the stairwell, I closed the door behind him and went right to bed so I wouldn't hear if he started meowing again (which JP assured me, this morning, he didn't.)
Man, though, I really want a cat. So, naturally, I dreamed about MysteryCat all night :)