I just got back to work, and in my mess of emails I found one from my boss with the subject "rumors." He's been offered another position, but doesn't know much information yet about who would replace him. However, it's a promotion to GS-14 for him, so he will most likely take it. We were finally settling in to having him around for the last 2+ months... and now he's going somewhere else. I guess it's really time to make better friends with his boss.