I wouldn't be without twitter!
Its more a personal tool for me (cf as a professional networking tool) - it enables me to scan the horizon of a whole lote of things (& people) I'm interested in (a lot are educational themes).
[ Multiple tweets from people saying what they are doing ( eg the "Im working at.... ) doesn't do it for me, usually ending up 'unfollowing' this type of tweeter. Tweeting for me is more about finding interesting ideas/thoughts/connections and humour ]
I wonder if our eTeachers almost live a dual identity - as 'subject teachers' (eg I'm a Maths teacher and have existing professional networks which meet my curriculum teaching needs) and seperately as an 'eTeacher' (with a similar, but distinct networks of online teachers where the curriculum isnt as important as the medium they are teaching in - such networks are usually based within a cluster)
If this is the case, perhaps these teachers feel there professional needs are already met, via multiple more local, existing networks
There may not be a percieved need for 'subject eTeacher' communities
- Just thinking out loud.
Another thing inhibiting the growth of such 'subject eTeacher' communities, is the lack of opportunity for vital initial 'f2f' relationship building opportunities - its very difficult for any online CoP to establish without opportunities to meet first physical (& establish tentative relationships).