Connecting Dell U3011 to retina MacBook Pro via mini DisplayPort
Solution 1:
Try resetting the PRAM and see if it detects the proper screen resolutions. If that still doesn't work, you could try cscreen (a command line tool to set a resolution) or SwitchResX.
Solution 2:
I found this blogger's page that says your cable connection works for at least one person. I would be looking at your U3011's firmware version and seeing if it is the latest, also keeping an eye out for any Apple updates for your machine. A Genius Bar appointment might help but without the monitor next to you it may not be fruitful. Can you try another retina MacBook Pro to see if it is just an issue with your machine?
If all else fails an active adapter like the Apple Mini DisplayPort to Dual-Link DVI Adapter would probably solve the problem - unfortunately this costs money but maybe less than it would cost you to change to a different monitor. These were absolute rubbish in the early days and caused me to return a Mac mini since it couldn't drive my Samsung 305T 30" monitor. But after seeing this knowledge base article about firmware 1.03 I got it swapped for the later version and it has been solid ever since.