The full frame Pentax K-1 DSLR camera will start shipping in Japan on April 28th. For the US Amazon lists the release date as April 25th:
B&H and Adorama have a shipping date as early May (both stores will be closed for Passover from April 22 till April 30).
The following new Pentax products will also start shipping on April 28th:
Via DC.Watch, Ricoh Japan