Um, today I've learned that I need to strip metadata from things before posting them on forums... My "PC" is running 10.6 - I didn't use iphoto to import this one and it still showed right side up... Well at least now you know your dad is competent...
Other than GPS data, there isn't a whole lot that is really worth anything. Other than say for a photographer to see what sort of exposure you took.
I just assumed iPhoto because that is what my dad uses. I always thought it was some metadata telling his apple products to rotate it. It still doesn't change the fact his pictures are upside down, he just can't tell.