This release fixes the bugs with SBM/Archives Page and WordPress 2.6. Subversion & nightly users: this release is revision 718. A list of bug fixes is here.
If you’re using the K2 Sidebar Manager, you will need to turn it off in K2 Options before upgrading to K2 1.0-RC7. After you have upgraded to K2 1.0-RC7, copy k2-disable-widgets.php (found at k2/app/includes/) to your plugins folder and activate it. This applies to all versions of WordPress that K2 supports.
Download: K2 Release Candidate 7
For the brave, here’s a list of file changes: