Good UPS software is a hard thing to find.  I've used apcupsd[1] quite a
bit.  As far as being able to talk with the UPS with any cable, this is
my choice.  I've used it under Linux and OpenBSD listening to a BackUPS
Pro series using smart signalling over the 0095 cable. 

Another good piece of UPS software seems to be NUTS[2].  I haven't used
it much in production because of cabling issues, but it looked promising
a few years ago.  

Nate

[1]. http://www.apcupsd.com/
[2]. http://www.exploits.org/nut/