You are a relatively prominent professor at a research university and you meet with a younger and (currently) unknown scholar. The younger and (currently) unknown scholar introduces herself to you and notes that you were originally scheduled to be on a panel together at another conference but has since heard that you will be unable to attend said conference. The younger and (currently) unknown scholar expresses her flattery at having been placed on a panel with you and regret that you will not be at said conference. The proper response in this scenario is:
A) Say, "I am sorry, too, and was looking forward to hearing your paper. Sadly, it could not be avoided, but the panelists are all so strong that I will not be missed at all."
B) Say, "Oh, they got you to replace me. The chair and I had put together a panel of just the two of us, but I had to back out at the last minute to suck up to my former advisor, the oh-so-famous-and-important-historian -- did you know my former advisor is the oh-so-famous-and-important-historian? -- he is oh-so-famous-and-important-historian -- and I know him -- by first name -- and will tell you personal details about his life to prove it -- and he's important -- and famous -- and was my advisor -- so I couldn't refuse because he is oh-so-famous-and-important-historian -- so I had to back out at the last minute and didn't think anyone at all could possibly replace me. But they found you. I have to go now."
If you are the younger and (currently) unknown scholar in this scenario, your proper response is NOT to slam back several more drinks and think "god, I must be a real loser." Instead, your proper response is to smile politely and think, "Dumbass, Be Gone!" Then, write a bitchy blog post.
Perhaps the last bit about the blog post is not the most professional response, and violates just about everyone else's blog ethic. Then, again, you have no blog ethic except not to name names in order to protect the bitchy, with the bitchy being yourself.