David Davies asks, about Twitter, "Why not just use RSS in the first place? You could create a lightweight RSS client that outputs your status, one-liner pearls of wisdom, or anything else you wish to tell your 'friends' about." And he concludes, correctly, "The benefit of a single service access point I guess is that it makes it easier to find new sources or feeds..." That's what took RSS so long to catch on; you could never find the feeds. I remember when RSS first started up, the aggregators (like 'News is Free') wouldn't publish the RSS feed addresses, so there was no way to find feeds. Any distributed system faces this issue.