Preserve modified time stamp after edit

For files within a specific folder, I would like vim to never touch "modified" timestamp at all. The background is that I use Bloxsom for blogging, which uses plain text files in ~/bloxsom as source of all articles. The article date (and therefore order of appearence) is based on modification date of the text file. I don't want article pop up like if it's *new* whenever I just fix a typo. (I do *lots* of them... :D) So far, vim changes timestamp and the original stamp is lost forever. This is OK and I want to keep it that way for most of files on the system. But I don't want that for the blog files - I can always touch the file if I need. Any ideas on how to tweak vim into this behavior?