The two major types of LCD panels are STN and TFT. They have different
pinouts (and different numbers of pins)
For a typical STN display, see
http://americas.kyocera.com/kicc/pdf/c47qaa21.pdf
For a typical TFT, see
http://americas.kyocera.com/kicc/pdf/t57qdg00.pdf
The number of pins and pinout of each type is pretty well standard, and
microcontroller mfrs are putting LCD controllers onboard nowadays (see
the Intel PXA 255/270 series for example).
I use both (in different products).
The biggest variation is the controller with the display (usually part
of the unit), although the I/O (as noted) is pretty much the same. Some
things do vary (such as frame polarity), but the basic conenctions are
usually the same within each family. Keep in mind I am expecting the
controller board to be attached to the LCD.
Cheers
PeteS