I´ve heard you will be able to ride on a dragon in NWN. Is it true?

No. There wont be anything riding anything else in NWN.

Though I wish it were possable :( (note my name)

That's a new one. While you encounter a couple of dragons, I have never been given the option to ride one.

Strange...
On a clan named "moonblade" or something like that they had a rank named "dragonwatcher". To become a dragonwatcher you had to have an own dragon...

It's probably something modded in, like a hack pack.

BTW, the term "owned" is slang for "killed." Could be that as well.