What I've found is that despite any matter of grousing on my part from day to day fluctuations in traffic, from backups on the Dumbarton Bridge connecting the Peninsula to the East Bay, crawling on 880 North, or navigating the 980 to 580 to 80 East maze into Emeryville and Berkeley, where RepairPal is headquartered, the minor annoyances actually have little impact on the average commute time. In my sample size, the time between consistent points is surprisingly stable.
For the local folks, my usual commute over the last few weeks has me taking 101 North from Sunnyvale, exiting Willow Road toward Dumbarton (Highway 84) and then going north on 880 past the Oakland Coliseum before exiting toward Emeryville. On the way, I've made it a habit of checking in at the same places each time - starting with the new Facebook Headquarters in Menlo Park, followed by the Dumbarton Bridge, then the O.co Coliseum (where the Oakland A's and Raiders play) and then finally RepairPal.
Today, the check-in at Facebook happened at 8:08 in the morning, followed by 8:12 at Dumbarton, 8:33 at the Coliseum and finally 8:49 at RepairPal. A similar trek that started 16 minutes earlier at Facebook saw the same three minute gap to Dumbarton, 22 minutes to the Coliseum, and a total trip of 42 minutes from point to point to RepairPal. Previous days show the total trip as 44 minutes from point one to point four.
So what and who cares? Not too many people, of course, which is why I toss all my silly check-ins to Twitter on a dedicated account (@lgloco) and don't post updates to Facebook. But by using the exact same route and checking in at the same places in the same order, it gives very precise indications of the time between points on any typical weekday, and lets colleagues anticipating when I'll arrive pretty much track my debut to the minute.
I'm also one of the people who keeps Google Latitude running constantly to provide closest connections with a precise knowledge of my whereabouts, but running Foursquare this way helps move the game-driven toy intro something more useful as a metric. If enough people followed the same approach, with consistent check-ins at specific points on a regular basis, you could safely estimate real-world timing between distances in practically any geography.
If you don't mind my nonsensical check-ins, you can follow @lgloco or see me on Foursquare here: https://foursquare.com/lgloco.
Disclosure: RepairPal is a Paladin Advisors Group client, where I am managing director of new media.