More and more people are using Posterous currently. And it is not difficult to imagine why.
Posterous is, quite literally, dead-simple. Just email your stuff, be it text, movies, images, documents, sounds, and it'll be published in a great way for everybody, or only the people you want to, to read. And the user support from Sachin and Gary is also excellent!
My whole web "life" is now centered around Posterous; I've set up 4 Posterous sites:
http://post.marcof.net - my main posterous where I keep my blog
http://pix.marcof.net - my photography portfolio
http://bibble-expert.com - the site where I want to post tips about Bibble 5
And last, but not least:
http://tweets.marcof.net - my tweesterous site where I put all my tweetpics.
The Posterous API enables twitter clients to post images to Posterous.
I've been using Tweetie on my iPhone for a long time, but that one still doesn't support Posterous.
However, an excellent alternative (with some quirks, but that's being worked on) is SimplyTweet (to be found here: http://motionobj.com/simplytweet ). SimplyTweet not only supports the Posterous API, but it is (I think) the only one that fully supports the multi-image posting in a correct way, namely not a post per image, but a post with all images for that post/tweet included.
Now all that needs to be implemented to make it even cooler for tweeting is:
- API search possibilities
- a way to have tweet text inside the body instead of post header
- an alternative to "twitlonger". Use posterous for longer than 140 character tweets.
And possibly more neato stuff....
In any case, the future looks bright for Posterous, it's about time to conquer the world!
Oh, I'm still waiting for Posterous merchandise ;-)