Well for the most part.
I can see someone asking me which site to use for their blogging needs. The answer is “it depends.”
I have been using Tumblr a bit longer than Posterous, but not by much.
With Posterous, I have been able for the most part, to post to other sites including this blog (within the Posterous inferface, not by email, sigh.), my TypePad blog , the college one, as well as Facebook and Twitter.
However, with the Tumblr one (known for microblogging), I’ve been pulling from my other non-work related blogs as well as finding non-work related links and posting them there. Of course, Tumblr also had the option to post to Twitter and Facebook.
Are you using, Posterous, Tumblr or both like I am? If so, how are you using them?