http://metro.kingcounty.gov/up/holiday-service.html
The main update is that for Monday, Dec. 29th through Wednesday, Dec. 31, Partial Holiday schedules will be in effect. See Metro's website for the full list of update.
Unfortunately, I'm back in NC for the holidays and missed the announcements from Metro, so schedules were not accurate for Monday, Dec. 29th. They should be up-to-date now.
As a reminder, you can actually see full scheduling information for your stop in OneBusAway. The timetable page for a stop can be accessed on the web from real-time arrival page for a given stop:

It can also be accessed from the stop search map:

Like more than a few people, I first heard about the updates through SLOG and STB:
SLOG: Happy Holidays
STB: Screw it, we're not running this week
STB: Follow Up: Partial Holiday Service



