Congratulations on your recent promotion! I also applaud your interest in having the developers "give back" to their communities.

I managed software engineers for about 15 years after being an engineer myself for many years. Overall I mostly enjoyed being in the management role; however, I did learn several lessons the hard way. One has to do with good intentions being misunderstood. So, IMHO, I'd be careful about tying performance reviews to their doing extra work in the spirit of giving back to the community. While I agree with the sentiment, some people may surprise you in how they react. Will they get a smaller raise if they don't submit to CPAN? Of course if the company is paying them for this work/time... which I wish more would do, then I guess there would be no issue.

Personally, I have found many people will do this on their own accord because they love what they do. Others will do it with a little encouragement... helping them see the bigger picture. Anyone who has to be coerced (not that you are doing that) probably is not going to produce what the community needs/wants.

Just some thoughts for your consideration.