I only met Callum briefly in Melbourne in 2007, right after I stopped volunteering for couchsurfing, right before he started volunteering for couchsurfing. A brief encounter with Callum was enough to know you're dealing with someone very smart and special. Later we started opencouchsurfing.org and regularly communicated online. I was happy to meet him again last summer in 2012. He wanted to start a new project and we brainstormed a bit about this. We were both avid users of ping.fm. I think Callum actually got me onto ping.fm at some point in 2007 or so.
Ping.fm: post to 20-something networks at once
Ping.fm was pretty good. There were some minor annoyances but overall it was a great way to post once and spread your message to tons of different networks. Facebook, Twitter, WordPress, but also Identi.ca, Plurk and many other fantasy named sites not used by many. But for an Identi.ca fan it was a great way to update your status on more than just identica. (For the uninitiated, Identica is an open source, slightly decentralized alternative to twitter.)
Then some day Seesmic, the slightly bigger social networking company with a nice looking product, took over Ping.fm. And quickly thereafter slashed the main feature that made Ping.fm stand out from the crowd. Since then there was no easy way for me anymore to post to Identi.ca, Twitter and FB at the same time.
Thus I was very happy Callum decided to build an alternative for ping.fm: Composer.io.
Composer.io: Post to multiple social networks
Now, half a year later Composer.io has become quite usable and you can post on multiple social networks simultaneously. It's actually a bit smarter than ping.fm as it will already allow you to post longer posts that will be automatically shortened for platforms like Twitter that only allow 140 characters.
Why post to more networks at once?
Personally, I have a bunch of followers of my twitter, quite a few friends on facebook. Identi.ca is not that active but unlike on twitter the links are dofollow links, so for seo I prefer to put links to projects I want to support with google juice on my identi.ca, but for social networking reasons twitter and facebook are much better. Like this I get the best of both.
Composer.io is a work in progress and your input is very welcome!