If you haven't been paying attention to Tumblr, here's what you need to know: Basically Tumblr is where all the smart kids between 17 and 24ish are hanging out these days. The strength of the platform is that it gives you an individual blog, but it makes it really easy to highlight other people's writing and add commentary. Because of this it forms a pretty good community, and there is a good chance to get a lot of reads if you write well, even if you don't have a lot of direct followers. Because of this it tends to target kids who are smart enough to add intelligent commentary to current events and cultural things, but who haven't really started publishing original ideas yet. Because of the size and influence of the demographic it's addressing, and because of the design strengths of the platform, I have every reason to believe that it will ultimately replace personal blogs for the vast majority of people. So in other words, adults will continue to have a Typepad blog or whatever for their business, but when you just want to write about your ideas you'll do it on Tumblr. The exception is for the people who are talented enough to make it onto the aggregators like Reddit, and committed enough to write every day; these people can rack up RSS readers fairly quickly, but everyone else will probably have a better experience on Tumblr and I expect people to continue to migrate there.