You're right -- obviously this isn't a post mortem or anything. The trends could reverse, and Posterous could become wildly profitable with less users while Tum

You're right -- obviously this isn't a post mortem or anything. The trends could reverse, and Posterous could become wildly profitable with less users while Tumblr has plenty of traffic but no money. Although it seems pretty obvious that both are headed for a combination of advertising/freemium model, and the revenue that comes from that seems pretty correlated to userbase size.