The Tactical Wire has
an article on holster options for M&P Shield. When M&P Shield was announced, S&W already contacted some holster manufacturers and there were some options, and now that it is on the market there are several other options too.
In the article, they go over Crossbreed SuperTuck, Galco Stow-N-Go, Uncle Mike's Reflex Holster, and Blackhwak Day Planner holster.
From: The Tactical Wire