I saw David Karp present Tumblr last night and its posting interface was really slick. It even allows people to suck in RSS feeds of other blogs.
I asked David whether he ever intended on making it go from suck to blow.
In other words, I have ZERO interest in maintaining two places for posting, like Fred and Michael are doing. I find it really annoying that I need to subscribe to two feeds for someone for basically the same stuff. I consider Tumblr a blog, mostly because I read it in a feedreader. Sure, I also consume Fred's last.fm feed and his Flickr feed, but I consume it in the context of those sites, which is what I want. I don't want my whole content experience dulled down to RSS...just blogs.
If the best part about Tumblr is the ease and format of posting, why not separate the two? Let me post a Tumblr style post to my Typepad account. Who cares where it's hosted?
Actually, to be honest, Flock already does some of what Tumblr does. I can right click a picture and autopost it to my blog and the same with a link. Still, Tumblr supports more formats.
And if Oddcast was paying attention, they'd propose a way to allow Tumblr users to quickpost a Voki. Perhaps that could be part of the business model there...paid inclusion. If you want a "post an X" button on Tumblr, you can pay them for it. The group of Tumblr users out there is a very influential and cool group...definitely people you want to market your widgets to.