The cache should be cleared after the page is edited and the current/updated form of the page should be displayed. However, with this problem the opposite is happening and when I edit a page and the page is reloaded the edits are not displayed until the user purges the cache manually.
OK, so, a few days ago I set the "cache epoch" -- the minimum time for the cache to report how old a page was -- as 21 Jan. We'd changed the titles to show "Reiseführer für ...", and this would let browsers and bots know that they should get the new version. However, I mistyped the date (it's in a funky format), and it ended up being a meaningless number that MediaWiki treated as "infinitely far in the future". So, caching wasn't working.
I've fixed the number so it should work correctly. You may need to manually reload some pages for a while, but it should correct itself soon. Let me know if there are further problems. --Evan 01:49, 24 January 2007 (EST)