We do that now with Dell stock references, there are some downsides though - some users struggle to give them accurately over the phone and they're hard to memorise. I've also found a few cases where the person setting up the machine has done an inadvertent typo in the hostname, but that should improve now we're doing the 'hostname from BIOS' thing.
The previous system, which I preferred was to create the hostname from a two character OS shortcode and a sequential number - NT001, 2K001, XP001. If a machine is reinstalled to a new OS it gets a number in a high range, XP800 etc.
These are easy to give over the phone and memorise but the main advantage is that when a user calls you immediately know the OS of the PC and the approximate age of the hardware without having to consult your inventory database. Another useful thing is if you're having problems with connections to an application you can tell the OS of those clients which are able to connect to see if there's a pattern without needing to cross-check. If you do do this you still need to have the stock reference as the primary key in any inventory databases in case the OS (and hence hostname) changes.