I'd consider myself mature. What are you wanting to get out of a community?<p>Sometimes my stories may interest or bore younger devs but man I like listening to them, sometimes they show me something new or Shiny, and sometimes I may even pass on some knowledge they can chew on and perhaps even use. I enjoy coaching and mentoring and value those interactions.<p>I think the mixture of people, skills and experiences are why we take part in any community really.<p>Edits: poor keyboard usage.
"Maturity" can be defined many ways (including age, temperament, or depth of skillset).<p>I doubt that there's any magical hiding place that differs from other developer hangouts. It's not like we are all out there despondently pining for new comp.lang.c articles while chasing those damn neighbor kids off our lawns.<p>Perhaps specifying a more specific metric (languages, environments, databases, etc.) could facilitate your search?
I've been developing professionally since 1999, and while I'm pretty active, I think in general "more mature" developers are less likely to "hang out online". This is a product of being more mature, which loosely correlates with age, which loosely correlates to family and property ownership and all the time-suck that goes with. Personally I just take what I find valuable from this community and try (not always successfully) to filter out the noise.