I've definately noticed that I'm becoming more forgetful. I'll do really odd things like put something down and literally the next second I can't remember for the life of me where I've put it, or I'll be thinking about doing something in my head, then all of a sudden just completely forget what I was thinking and have to seriously think hard to remind myself.
I NEVER used to be like that, so I wouldn't be suprised if it is the effects of long haul flying, or more likely sleep deprivation caused by the long haul flying! Oh dear!