I would say yes there are. People look for gold all over the world. If this is a place where gold has known to be found you will get someone prospecting if only for a hobby. Some do it for their holiday or as a weekend pastime, it can be a fun thing to do.
In 2010, there are people that are still mining for gold in Sonoma, Ca. In fact, tourists visiting Northern California can join several tours that take them to gold "hot spots" for their own chance to strike it rich.
This question seems to be off-base. Sonoma isn't in the gold country. A question that would make more sense is "Are there still people gold prospecting in Sonora, CA? And the answer would be yes, there are people prospecting in the Sonora area, if not in Sonora proper.