There are a lot of local IT communities in most mature software development areas like Moscow, London, San Francisco and now in Samara. Some of them supported by companies and exist until they would solve some business goal: hiring, reputation, etc. But I want to discuss benefits of 'open' communities driven by local enthusiasts and for no profit.
Important notice - they also should be open for contributors and 'fresh' blood.
It's cheaper to support OSC instead of running your own.
- No need in dedicated person responsible for community, only contact person for communication with activists.
- No need in a huge marketing budgets. Networking inside community will share anouncements and news.
- No need in non-local speakers. Experts from different companies will give talks on meetups and conferences.
Motivation for employees
A lot of developers leave companies because of unreal thoughts and hopes about better place. And new company would suffer even more than an old one, if it would get newcommer and would screw his expectations. If you have open community, it's easier to understand what you can get from one place or the other and developers would happy if they can share or retrieve some knowledge from other members even if they work in different companies.
Only weak companies could be scared of open communities and cross communications between developers. Strong company would gain a lot of benefits in terms of motivation if it would support OSC and their activists.
And the last pros - local. It's easier to do your business if local competition between players is stronget than between own region and bigger one (for example Samara and Moscow). I knew many examples when good developers move to capital city because of not only salaries, but activities, connections and atmosphere. If you contribute something in local environment you will get feedback in terms of professional growth, variety of specialities and in fact - business possibilities.