Well, as (perhaps somewhat) expected, as of today UA has changed the pet policy on all 3-class 763s: no in-cabin pets in C or F. This is true even if the plane has not yet been upgraded; just like with the seatmaps, UA is being proactive and is treating reservations on these flights as if the plane will be an upgraded one. So, no more in-cabin pets in C on any 763 from today.

(Unfortunately, this totally screwed my winter travel plans, and I'm really bummed right now. Last week, I asked about pet availability 3 or 4 times and none of the agents mentioned that this policy would be unilateral. Today, it's a done deal - the computer rejects any attempt to book pets into C on a 763WW, even if the seatmap still shows the old configuration. Not a good day for me - the one time I was actually thinking I could upgrade, and poof, shot down.)