I just pushed the King County Metro September service revisions to OneBusAway. This should hopefully bring everything up to date for the changeover this weekend and fix a few bugs people have found in the current schedule.
However, I've already noticed some new bugs with the new schedule data. If you find any of your own, please let us know.
I'd also point out that Link Light Rail schedule data was included with the update. Metro calls it the 599, so be on the lookout. You can look at the full route here. Sadly, I don't yet have real-time arrival data for Link (bu I am working on it!), so you'll have to settle for static schedule data for now. I'm curious how the schedule matches up with actual train operation. If you are able to compare, please let me know what you find.
P.S. Note that the iPhone app isn't using the new schedule data yet, but I will push the update to that tomorrow night.