The choice of service was pretty obvious — while Twitter uses proprietary software and has custom Terms of Service, identi.ca is based on software under the GNU Affero General Public License, and the contents are CC-BY 3.0 licensed.
$ git clone git://gitorious.org/laconica/mainline.git
My account details are available under http://identi.ca/uwehermann, where I'm posting smaller announcements and notes about random technical stuff I'm working on (slightly more regularly than in this blog). Sometimes I use the web interface for posting, but using the Jabber integration available at identi.ca is even more convenient. You can both be notified of new posts ("dents") in real time via Jabber, as well as post your own dents from within your Jabber client, which is nice.
identi.ca seems to become more popular every day, which will hopefully make the proprietary Twitter pretty much irrelevant sooner or later.