In explaining Union Square Ventures investment in Tumblr, Andrew Parker goes out of his way to distinguish the service from traditional blogs. But in explaining how Tumblr does not compete with Twitter, in which his firm has also invested, he makes it clear that, well, Tumblr is a blog — while avoiding the b-word at all costs. Tumblr is a just blog, and doesn't compete with Twitter. While services like Tumblr, Twitter, Jaiku, and Pownce are lumped together as microblogging tools because of their brevity, users recognize the dramatic differences in the software behind them and the experiences they create. They are more than blogs. Brevity may be the soul of wit — but it's not the ghost in the machine.