The Linux ecosystem is increasingly centralized and most of the organizations that are centralizing it, like the Gnome project, are actively discouraging contributions that don't match their agenda. This is reducing the importance -- and cohesion -- of any community. It's no coincidence that many people are finding less common ground in software they're all using than in software they're all hating.
The only Linux community I'm still vaguely in touch with (I read the mailing lists and sometimes the forums) is the Gentoo community. Largely because my only remaining Linux machine is running Gentoo. It eats a lot of my time, but stubborn USE flags control seems to be the only way to get a usable Linux distribution lately, and I'd rather spend an extra hour a week configuring it carefully enough to keep crap software out than spend a whole evening each month dealing with sudden breakage. It's not necessarily a friendly community, but most people seem to know what they're talking about.
Frankly, as bitterly as it may sound (and it's coming from someone who started using Linux just in time for the 2.0 to 2.2 switch), I'd rather recommend the OpenBSD community.