I work with a few security pros who blog. As you suggest, you can't tell people specific problems you're facing at work but you can do some interesting things to get your knowledge out there:

1. Make educated guesses about real incidents you were not involved in. Talk about how you would have solved this problem if it were you. 2. Set up sandbox environments to demonstrate attack vectors and detection methods. Even "dumbed down" versions will help newbies out if you want to keep your more "advanced" versions secret. 3. Talk about tools and services instead of specific incidences. Most of the info about how they work is public, but you can showcase your understanding my summarizing and giving commentary.