Personally I think that's not very useful - I don't often find myself looking at older blog posts and if I do I either use Google or the site's own search funct

Personally I think that's not very useful - I don't often find myself looking at older blog posts and if I do I either use Google or the site's own search functionality. Your system seems to require content to be created in it to be searchable. It's an interesting idea, but I wonder how many people are actually really trying to locate old content.