I've also written supporting libraries to display both text and PNG files, although don't expect too much from a 128x32 monochrome image!
I've uploaded my notes and libraries here:
Coding it is as simple as:
my $lcd = BeagleBone::SSD1306::Text->new( rst_pin => 'P9_15', dc_pin => 'P9_16', # remainder of pins must be connected to SPI pins ); $lcd->display_string("Hello world!");