There are lots of laser printers which work with Trisquel purely because they
support postscript.
Dell doesn't design printers either last I checked which means somebody else
did and it is 100% certain that it depends on those companies which actually
designed the printer having released the code. There probably are some Dell
printers which are free software friendly. Dell was selling printers
originally which were made by HP. However they have since moved on to working
with others (Lexmark, and probably others).
The best thing to do is look at HP's documentation. There are several places
to look once you have the printer model looked up. One of them being the
firmware, plug-in, and then HPLIP version. There may be variations of a
printer model though and I can't confirm that all variations are going to
work.
And as always we do sell a handful of Trisquel-friendly printers.
One other note. You probably won't have support out of the box for any HP
printers readily available under Trisquel 6. The HPLIP version included in
Trisquel pre-dates HP's current line-up. The printers we ship on the other
hand do all work with Trisquel 6 out of the box.
