What rab777hp is is true, it is something that can be accomplished. The video circuitry on the logic board is the same for the high and low resolution screen options, as is the video data cable (LVDS). However, I have not been able to confirm that the early 2011 15" MBP utilizes the same LVDS cable as the previous years/models to enable you you use the screen in your comment. If the LVDS cables are the same, the LCDs are interchangeable.
The only thing you may have to do in addition to changing out LCDs is change your display profile - you can find a number of working ones on Macrummors for various screen models/(manufacturer's part number) to get the high resolution with good colors, etc... The manufacturer's part number is on the back of the LCD. A cheap easy way of getting the picture you want with the new LCD is to back up your data. Format your hard drive. Then reinstall your operating system. During the install the OS will run a query for the hardware installed, including the LCD, and set things up properly.