Why am I using it? - well, I came across it in the Edublog Awards 2005, thought it sounded interesting (buzz words like 'open source' and 'learning' caught my attention) and thought I would give it a try. I have been experimenting with blogging (especially of conferences) for about a year now; I have been involved in online/open/distance education for over 15 years (as both student and educator), and I have an active interest in free/libre/open source software (FLOSS).
I'm not sure at the moment what Elgg will give that other online learning environments (eg Moodle) can provide - or other online communities, like Academici - but I will play around with it a little bit for personal use and then see if/how it can be used for educational purposes.
Keywords: education, Elgg, open source

Comments
just wanted to say that I've made an ELGG site myself (http://elgg.net/karloy).
BTW, there seems to be an ongoing collaboration to integrate ELGG and Moodle disseminated on the ELGG "Latest News" site; A new collaboration (December 16, 2005): "We are delighted to announce that Elgg is collaborating with the NZOSVLE Project Team - Catalyst IT - to develop integration between Elgg and Moodle."
Cheers
Karl