I'm a pretty big fan of Google's 20% time. To those who don't know, this is a policy where employees are allowed to work on "their own" project for 20% of the time. For some managers, this would seem terrifying or just stupid. However, in reality it allows your employees to work on what they are passionate about and, shocking I know, sometimes they have good ideas and their ideas make you money. At the very least they gain experience. I'd much rather have an employee learning new things on my dime than stagnating on "their own time."
However, this policy is mostly talked about with programmers. I am not really a programmer. I play one on TV occasionally, but I'm really not one. I'm....something. Not sure what. Lets call it an "Infrastructure Administrator". My company encourages me to work on what I am passionate about. I just so happen to be passionate about drupal and mysql and memcache and distributed caching and load balancing and cluster management....and bikes. Sadly, they don't pay me to ride my bike yet. However, mostly I'm passionate about drupal and I work on the drupal.org web infrastructure.
I get a lot of my experience from working on the D.O. infrastructure. I learn new things and am able to work with the best in the business (Gerhard/David/Derek/Damien...the list goes on and on). I cannot tell you how much this benefits me and my clients. They don't know this, but my clients owe a huge amount to the Drupal community for giving me the opportunity to work on the D.O. cluster and work with the people that I do on an almost daily basis.
Yet, where are all the companies encouraging their systems guys to go out and get involved? Open Source companies like to pound their chest about programmers giving back, but where are the sysadmins? The value in getting your systems team to contribute "their" time and get involved is not just helping the community. Make no mistake, its training. Its continuing education. Its giving your guys a chance to go out to a real infrastructure, find a big complicated problem and find the solution. A year later when in a meeting they note that "They have solved this before"....the benefit will become obvious. They may end up having less time, they may end up being a little more busy, but would you rather have an experienced sysadmin who has honed his or her skills working on many large infrastructures handling your systems or a sysadmin who has plenty of time and plenty of knowledge gaps doing it?
Its worth the investment.