The sherlock-holmes tag is apparently for Works based on the British Detective created by Arthur Conan Doyle. While questions on all Sherlock Holmes works are to be tagged with this, questions on Sherlock Holmes (2009) appear to be only tagged with this single tag.
I must admit my first reaction to this was that we shouldn't have a tag for 'generic works about ACD's Sherlock Holmes. However I thought about an equivalent character, and looked up the james-bond tag which is widely used as a generic tag for the character / movie franchise. So I think you are probably right.