"Known bugs" for a given release means bugs that were known about, and were announced to the list before the release went final, but were not fixed. Generally these bugs are put on hold because the fix is not obvious, or the problem is subtle and the fix would require lots of testing, or the functionality involved is rarely touched... A Swiki page for a "known bug" in a given release should explain the bug, give steps to re-create the bug, and explain why the bug was not fixed for that release.
Also, a "known bug" page should include suggested fixes and/or SUNit test packages, if there are any.