Give the man a break!!
Jesus Christ, give the guy a break!
If he shows up, he'll be bombarded by a gazillion questions about his health.
If he does not show up, there'll be rumor and speculation, like this article.
If I were in this no-win situation, I'd blow off public events, too. Externally, nothing will change, but in the meantime, at least I wouldn't have saved myself the aggravation.
Regarding the IM thing, maybe Steve's just twittering these days...? ;) (And, yes, that was a joke -- there is a reason why "twitter" begins with "twit".)