Actually there is a working port of Mosaic (well, working is an
over-estimation, it renders nothing correctly) and even a fork
(Mosaic-ck). The problem is, it is of limited use nowadays (much less
than Trinity's Konqueror as a browser). Besides, its interface is quite
ugly.
Partly Mosaic and Netscape were responsible for the mess that the Web
has become, but then again they were quite innovative in their time. But
using them in present-day would be frankly pointless.
--
Mavridis Philippe