Lots of discussion in the local newsgroups about snake sightings -- there've been a lot of them lately. As a general rule, leave 'em alone, but it's good to know which ones are harmless and which ones are not. These photos came from folks who saw these snakes in their yards:
The pacific gopher snake can be big, but it's harmless (to you, unless you're a rodent). Keep this one around.
On the other hand, the diamondback rattler (see its distinctive markings) needs to be avoided!