To date, in 2013, I have noticed that many homes are selling prior to even hitting the MLS. They are either marketed within a large broker's agents as a "pocket listing" (meaning coming soon to the MLS) or with a Coming Soon sign in the yard. This is particularly true in the luxury market.
This means buyers should 1) work with a Realtor who has a large network of agents, 2) get pre-qualified from a lender, so that a pre-qualification letter can be submitted simultaneously with an offer, and 3) drive your desired areas frequently to discover "coming soon" signs and call your Realtor immediately to get a private showing.
Lastly, be patient...it may require submitting offers on numerous home before you get one!
Keller Williams Realty