Well I'm just about to pin mine in that area.
EDIT: or I would be - complains needs new google app key in Opera 10 on Ubuntu. Overuse? I'm SW16 anyway.

I am also really considering starting a mobile linux enthusiasts group, via meetup.com (I already manage a meetup group through there so one more is easy and doesn't cost any more). Meets would be somewhere central London and maybe for other exhibs/relevant days out and talks too.

There used to be a "mobile developers" group that had 5-10 regular attendance with 1 regular meet a month but the organiser dropped out and noone wanted to take over. I think if the subject is broadened a little (not just devs) it could work better?