My colleague made a public post on my personal facebook wall?

[BB]

You're right, this is not ok. On the other hand, you should have contacted your workplace directly when you knew you were not going to be able to make it. It could also compromise your standing in the workplace if you make a big issue of it.

I suggest you just delete this from your FB wall and forget about it this time. However, if the same person makes a habit of posting disparaging remarks on your FB wall in future you will have to ask them to stop - tell them it could affect the industry's perception of your company.