ServoMaster: Driver Release Notes
Basically, you're likely to run into a single problem, namely, installing and using RxTx (which you'll need for all serial drivers to work).
For me, version 1.4-15 worked (and still works, with uptime measured in months) perfectly, however, it can be a real pain in the neck to compile on new platforms, and I don't even remember if I ever compiled it successfully with JDK 1.5.
Recently, the situation [allegedly] improved, and versions after 2.1-7pre20 may work without segfaulting within a minute. Caveat emptor.
Moreover, to make things more seamless, javax.usb is now prepackaged with ServoMaster, so it should be mostly invisible to you.
The change was quite drastic and backward incompatible.
Should you run into problems with jUSB-based version, try javax.usb-based version first. Should you run into problems with javax.usb-based version, please report them so I can fix them right away.
You will run into this issue, no matter what interface you're using. You may not notice it at first if you're fiddling with your devices while running your applications as root, or being logged in as the same user you run your applications under, but you will definitely notice them as soon as you start your application as a daemon, or you're working on a remote box with someone logging in and out.
Different distributions handle this issue in a different way, so there's no single answer. If you had run into this issue, and were able to successfully resolve it in an elegant way, your feedback would be much appreciated and aggregated into this site, with all the credits given.
For USB adapters, hotplug is the starting point.
For serial ports, you're on your own, until someone (maybe you?) donates a universal solution.