Why tumblr 3.0?
First one was hosted on tumblr as Net 2.0 tumblr.
Then it was moved to self-hosted solution from Gelato. Despite this blog network running on WordPress from early days, the micro-blogging or quick sharing features were made available quite late in WordPress, leave alone the formatting of posts based on different types such as image / video / status / link etc.
Later Gelato platform stopped receiving support from its creators and by then, WordPress had already matured into a micro-blogging platform. Hence this third avatar of tumblr as tumblr 3.0. Every single post from the starting days of tumblr 1.0 is available on this platform while maintaining the original sanity.