Anytime we get a cheap creature retrieval spell I am happy. I loved playing with Garruk Relentless in Innistrad because he allowed me to bring specific creatures out of my deck repeatedly. Signal the Clans is a nice two cost card that lets us have a creature, but also kind of tips our hand to the opponent. We essentially pick three different creatures from our deck and reveal them. Then you get to pick one at random and put it into your hand. This makes for a nice, early game setup. You can grab 3 different creatures from your deck that you know you can use in turns 3-5, but of course you have to way the risk of letting your opponent know what at least one card in your hand is.
If you are playing against blue, then cast Signal the Clans at the end of your opponents turn if they have tapped out. That way you can have your creature and guarantee it will hit the board on your next turn. If you are going against black though, be careful as tipping your hand/deck may cause something nasty like Slaughter Games to come out later.
I think this guy will at least end up in sideboard play for standard.