Tumblr is a new web service similar to Twitter. When you set up an account, you create a tumblog. Anything you post to it, then gets posted to your tumblog. It’s similar to other blogging services in that, your account can be hosted on their site, or you can purchase a domain name and point that at your tumblog.
What makes it different from Twitter is that you can post more than just text. You can post a photo, a quote, a link, chat excerpts, audio or video. It is different from a blog, in that there is no way to comment on posts. There are also no other bloglike features like categories or blogrolls.
So if you already have a blog, Twitter account or a Flickr account, why do you need another service to post your stuff to? Well, you don’t really. But what interested me in Tumblr is aggregation. You can import posts from other services into your Tumblr account. Services that can be imported include Del.icio.us, Digg, Twitter, WordPress, VOX, Blogger, LiveJournal, YouTube or any RSS feed. So rather than post the same info to different services, you can post to each service, import to Tumblr and display everything in one place. What this means is that you can track me on all these other services, or you can track me in one place on Tumblr.
I created an account to try it out. You can see my tumblog here. I am still trying it out, but my first impression is that the import feature doesn’t work like I hoped. It does import posts to Twitter. I added this blog’s RSS feed so it should import a link to each post. I also added my Flickr feed to it. It doesn’t import any old info, only new posts, but it takes a really long time. It took over 6 hours to import the Twitter posts.
So my advice is just to keep using your other services, unless you want to aggregate all your stuff like I am doing. You might want to try making this your primary blog if you aren’t using any other services, but be aware that it lacks important blogging features. I do hope they will continue to work on Tumblr and improve it. I think it has a lot of potential to be a really good service.