Hi Valve, here is your un-scheduled reminder that a part of your community wishes they could search their expensive libraries based on the same User-Defined tags used in the Steam Store. Any ideas when can we have a Library feature like this implemented?

Yes I know it's been requested many times before. We're still hoping and waiting - since it is practically just recycling metadata and indexing it in Library view. Also, since it presumably benefits most the customers who've given you the most money via Steam Store (and have gigantic libraries they need help searching through).