If You're Headed Home Tonight to the Westside, You Might Want to Use A Surface Bus!
Based on tweets from various folks I follow on The Twitter, as well as a report from the Examiner, the Muni Metro tunnel is pretty much closed from Embacadero to Castro Station, after an N pulled out cables and concrete from a wall (?!?) in the tunnel. Sure there's a bus bridge, but you know how that ends up.
Right now your best bet is to take a surface bus home to the westside. I guess that N Judah Express Bus is coming in handy today - hopefully it can handle the load as people try to get home. Personally I'd take any one of a number of buses - the 6 Parnassus can take you from downtown to the Inner Sunset, the 71 can take you there too, and to points of interest in the Outer Sunset. If you're headed to the Way Outer Sunset, then the new NX is your best bet.
If you want to get really crazy and are over in the Financial district, you could take a 1 California to the 44 O'Shaughnessy, but that's a bit of a stretch.
Personally, I find this particular catastrophic Muni blowout to be ironic, given how Soon To Be Ex CEO Nat Ford was spending all day today spinning his years in office. Joe Eskenazi at the Weekly, however, expertly called BS on that today.