It's a niece! My sister and brother-in-law (although mostly my sister, effort-wise) had a daughter, Allie Charlotte today at 12:28. She is healthy and, I assume, beautiful.
Update: She was 6 pounds, 4 ounces and 19 inches. And here she is:
(I'm going to go ahead and let my sister decide whether she'd like to post photos involving herself just post-giving birth. You're welcome, Lisa.)