Thanee,
Actually, one of my player has played a halfling wizard for about 2 years. But I am saying halfling to be not that good for a wizard as I have seen many cases when the combination of slow speed and the lack of low-light/dark vision has prevented him from casting spells.
And, even if a player knows that his halfling is a very weak grappler, that knowledge does not help him when a big purple worm emerges from earth. And, a halfling paladin cannot just run from a tiger when his job is to fight monsters in melee and protect party spell casters.
CRGreathouse,
Small size also harms wizards and sorcerers a little bit. The combination of low-strength and small carrying capacity is a big problem. For example, if you put 8 to strength when making a halfling wizard with point-buy, now his carrying capacity is only 15 lbs for light load (str 6 and small). Now, until he buys a HHH or a bag of holding, a travelling wizard must seriously worry about the total weight of his gears. This is worse for a Halfling rogue ...
I still think a Gnome Wizard is very good choice. But I cannot find much advantage on choosing Halfling for a Wizard.