K2 has announced a release date for blackpearl! The date will be August 6. From the press release:

K2 blackpearl gives business and technical users the ability to collaboratively design, assemble, execute, monitor and optimize dynamic business applications. K2 blackpearl includes business process management capabilities. Although blackpearl's capabilities far exceed those of K2's previous offering, K2.net
2003, existing customers can upgrade easily.

I'm not sure if pricing and licensing information is currently available somewhere or will be published on their website; as I recall for the previous version you had to inquire about it.

K2 will present information and product demos this week at the Microsoft Worldwide Partner Conference 2007 in Denver, Colorado.

You can view the full press release here.