Notice
The cache is activated again for a third round of testing after last night. If you aren't logged in, don't be surprised when pages don't seem to update or if visiting a thread that on the main page claims has no new posts suddenly has a bunch - it's all down to when the cached version of a given page was saved. The cache is "dumb" for a reason - tying to invalidate cached pages on the basis that a linked page changed would require code that would defeat the entire point of trying to reduce server load.
If, when you log in, something isn't right, then please flag it up.
Only the main index, forum index and thread displays have any caching.