I received a tip that all Pentax K-1 pre-orders will be shipped with a free D-BG6 battery grip ($199 value) similar to the free XQD card and reader that will come with the D5 (I would take this with a grain of salt, I am still in the process of establishing my Pentax/Ricoh sources of information).
The Pentax K-1 is expected to start shipping on April 22, 2015 in the US: