Apple's current 24" ACD's have a poor to fair Adobe RGB gamut rating and do not compare as well (color gamut wise, and color calibration) against the cheaper ($550 vs $899) HP LP2475w 24″ Monitor.
http://blog.david-kennedy.com/2009/10/15/apple-cinema-24-versus-hp-lp2475w-24/
As a photographer who relies upon having the best color accuracy possible, none of Apple's cinema displays have been up to the task for quite awhile now - even the 30" is woefully lacking in color accuracy for color critical work.
NEC, Eizo, LaCie, HP, and a couple of the Dell's (2707 & 2408 and 3008WFP's) have bypassed Apple in this very important area quite awhile ago. Apple use to rule with their LCD displays when they were the first to introduce a high resolution (1920x1200) 23" ACD way back in 1999 - over a decade ago. Since then, Apple has continued to produce well designed and very respectable LCD monitors that compare favorably to similar LCD offerings by other companies - except in the area of cost. And more recently, with the release of their 24" LED Display, Apple seems to have notched downward in providing a higher-end, professional grade LCD option when it comes to not only color accuracy, but in overall features (limited connectivity options - along with proprietary mini-display port interface), and having only a "glossy" panel option - which is a definite no-go for many design, video and imaging professionals.
Apple will at least have to match - if not exceed Dell's very well received newest 27" LCD monitor: the U2711.
http://accessories.us.dell.com/sna/productdetail.aspx?c=us&cs=04&l=en&sku=224-8284
And Apple won't be able to charge much more than Dell's newest 27" ($999-1099) and they will also have to at least offer an option for a matte screen version of it if they want to be taken more seriously as a viable option with higher-end imaging and design professionals.
If they just offer another 27" LED sporting a proprietary mini-display port, glossy screen and less than 90% Adobe RGB gamut for more than $1400, then except for a few Mac only diehards - it's not going to turn many heads, or entice non-mac folks to buy one.
I currently have the great pleasure of working with one of the very best LCD monitors available right now: the LaCie 730 30" LED 14-bit monitor with BlueEye PE. I purchased one for $1500 Refurbished. If Apple were to ever offer anything on this level in a 30" format - then they might be back in the game of professional, high-end imaging.