Since iron sights have been introduced will there be an option to turn the little target reticule off? I think it would really improve the realism and make it more fun at least for me.

probably, it was mentioned that the options menu have been pumped with steroids so you can change alot more now

Couldn't you turn it off in Fallout 3? I was always under the impression that you could, though seeing as I never would have used such an option anyway, I could have remembered wrong. In any case, I'm pretty sure Obsidian has said that whether the crosshairs will still be used when using the iron sights or if you actually need to aim using the sights themselves will be an option that can turned on and off, though if you choose to aim using the sights, the crosshair should still be available when firing from the hip, if you don't want it in the game at all, I can't say whether such an option will exist or not.

People never looked in the options menu of Fallout 3 huh?

You could turn the crosshairs off, turn the HUD off, change the color of the HUD and the pip boy, customize the controls any way you wanted, make certain noises like footsteps louder etc. etc.

Yes it has been confirmed that you can turn off the reticule while using iron sights
I believe the option is called "true iron sights"