Here’s a Gem for you. A Nice pdf that walks you through the details on permissions required for the K2 for SharePoint piece. The core of this information is also available in the help documentation for K2 4.5. But, this is a must read for everyone looking at installing K2 on a SharePoint environment.
K2 released a beta recently to Provide Support for SharePoint 2010. This beta requires the latest update KB1140 for the 4.5 platform. You can download it from the customer portal. Both Sharepoint Foundation and Server are supported for both blackpoint and blackpearl with this Beta.
With K2 we can wrap Sharepoint Lists with Smart Objects. We would configure an SmO to map to a List. So that when an entry is created in the SmO it writes to the List and when you add an entry in to the list directly and call the getList method on SmO it returns all the list entries from Sharepoint. In short this SmO becomes a data access object for that Sharepoint list.