"When you believe in a thing, believe in it all the way, implicitly and unquestionable. " - Walt Disney
Q:

Dear 100 Hour Board (probably Mama Sleuth),

Who updates the Church-related Wikipedia pages? An hour and a half after President Hinckley died, when all the Utah news sites were busy, his and President Monson's Wikipedia pages were already up-to-date.

-Olympus

A: Dearest Olympus ~

Due to recent events, Mama Sleuth has become very, very busy. Instead, we turn to Laser Jock! Who, ironically, is only very busy.
I found the first person who updated Wikipedia with Pres. Hinckley's death. It was Wikipedia user Snocrates, at 03:07, 28 January 2008 UTC (which is 8:07 pm on 27 January 2008 in Mountain time). (You can see the last 500 edits here, which should last awhile)

For the rest of the question: like with other Wikipedia pages, normal people update the pages as they get news. I've been surprised in the past by how amazingly fast people update Wikipedia--there's no need for inside sources. (Besides, it wasn't until an hour after the fact that someone updated it, anyway.) Since Snocrates updated there have been quite a variety of other people editing it, as with any hot topic.
So, m'dear, it is not any official person... it is just the first person obsessed with Wikipedia to hear the news.

~ Dragon Lady