"I double checked ACAD version 2008 which I have here and it does not seem to support it, so I wonder if that's something that they added back in recently, or if possibly it is some kind of extension pack that you got along with Inventor or something like that?"

IGES has been standard for as long as I remember (not an Inventor add-in). They might have axed the command [igesout] as legacy...? Anyway, it's located in the export menu now. Try the [export] command in 2008. I only have 2012 installed currently.