These are currently in the market - check your local Best Buy! 

Apparently, Nintendo got a better deal with the LCD screen business, and improved the current GameBoy Advance SP with a brighter BACKLIT screen (not frontlit like previous version) AND a better battery life! The screen quality is better than the Nintendo DS’s, and is almost as good (if not as comparable) to the Sony PSP’s.

Picture taken from IGN member in the Gameboy forums:

The pros about the new GBA SP is:
1.) Brighter, more improved screen Backlit screen.
2.) Size of screen is more easier on the eyes than GB Micro.
3.) Clamshell design to protect screen.
4.) Compatible with all GameBoy games ever created.
5.) Battery life lasts up to 13 hours with backlight on opposed to 18 hours with backlight off from old GBA SPs

Check this forum for more info: http://www.ga-forum.com/showthread.php?t=64019&page=2&pp=50

Shots from the forum:

Pictures taken from another website:
Compared to PSP:

Compared to DS:

Playing Metroid Fusion: