This is not the case anymore. According to a post an the german mailinglist (and also to my observations) Mapnik now renders tiles much closer than Osmarender. So edits should be visible within an houre in Mapnik (maybe not instantly at all zoom levels).

If someone finds the official announcment about that new behaviour could he or she modify the entry in the FAQ: “3.5 I have just made some changes to the map. How do I get to see my changes?” ?