It uses the first posts... but if you make them sticky.. so that they appear first.... it'll work.
What we need is a hack that "duplicates" posts in threads.. then you could duplicate needed posts into a "news" forum and delete the duplicates when you don't want them on the front page anymore.
Don't know if we'd ever see a "duplicate a post" hack... it's way beyond my ability, but I'm guessing it's complicated.
