I've got the official word on the LaserWriter Pro 600 memory
upgrade.

I just got off of the phone with the quite friendly Donna Rossi
at Apple Customer Assistance.  She tells me that those who
purchased the LaserWriter Pro 600 in a 4 megabyte (300dpi, no
greyscale) configuration should contact their original dealers
who are supposed provide the 4-meg memory upgrade.  For those
who don't know, the extra 4-meg will allow printing at 600dpi 
or greyscale (at 300dpi).

If the dealers have questions, they should be directed to their
hardware support numbers and/or Apple Customer Assistance 
1-800-776-2333, 408-996-1010 (corporate number).

Regards,

Glenn