Since Bochs version 1.4 it's possible to use VESA graphics. There are some limitations in the current implementation, but in general it should work ok (we have run several test programs, the XFree86 VESA display driver, etc)
Current limitations:
only 8bpp modes are supported (no 16bpp, 24bpp or 32bpp!)
banked mode is very slow (if you can, just use Linear Frame Buffering instead!)
only 320x200, 640x400, 640x480, 800x600, 1024x768 are currently supported
Interesting Facts:
You need a display driver capable of using the VESA bios for this to work (a recent XFree86 will do, Windows 9x/NT/2K/XP probably will not work 'out of the box'.
Currently the VBE2 extension should be supported ok