Unicomp, the company formed by a staff buyout of IBM's keyboard division, offer a real mechanical in Sun "UNIX" layout: http://www.pckeyboard.com/page/product/40PSA

It's a dream to type on and has the 'right' layout. It's not cheap or quiet, but it really is the best keyboard I've ever used. I'd kill for an affordable HHKB-sized Model M from Unicomp.