Obviously, but it doesn't fix the inconveniance, and rechargable AA aren't as good as built in rechargable batteries (my rechargables for my GBA wore out after a couple years). They're better than regular batteries, but it would still be worth have a recharable battery built in.
Internal rechargebles are exactly the same as aa rechargeables... They have close to the same recharge time as aa's and same amount of recharges as aa's too.