Since Momma has declined to hide them in a secret undisclosed location, the kittens have been hanging out in the carrier while Momma hides under the bed. Momma is wild (as in "feral", not as in "let's party"), and for some reason she shows little interest in the babies other than to nurse them (thank God for that) and clean them. She also comes out to eat, drink, and use the litterbox, but other than that, it's Underbed City for Momma. So I took the door off the carrier, and that's where the babies prefer to hang out.
And yes, I am a little worried, especially since I have to take them for a vet visit later this week, and I have no idea how I'm gonna get Momma out from under that bed. She's one bad ass cat, and I'd hate to lose a hand or something in the process. I guess I'll just keep spending lots of quality time in the bedroom (heh), playing with the kittens and peering under the bed trying to connect with Momma.
But! Kittens! Adorable kitttens! The shelter volunteer said they were four to five weeks, but judging by their size and crawling-around skills (or lack thereof), I'd put them at closer to three-and-a-half weeks. And they are extremely friendly and show no fear of me whatsoever, which is very cool. Very often when I peek into the carrier to see how they're doing (most of the time they're sleeping all piled up together), one of them will open up its eyes, see me, and come tumbling out, and then the others are like, "hey look! the human!" and they all come out to play.