Before computers, it was personal use of phones. Generally these things are like speed limits, they aren't enforced that much, but will sometimes use them to make examples.
In my work experience this is one of those polices that is used to get rid of employees that people don't like. I've seen employees fired for similar infractions when the office's political environment changes.
Also, having had to do investigations on employees, it's amazing what kind of logs are kept - for a very long time - detailing the activity of specific computers. I'd head Ubergeeks warning on that one - if you plug into a network, a log is generated.
But, I want to add one more cautionary element to your decission making. BY stating the equipemnt is for work use only, they are also pretty much telling you that you should have no expectation of privacy (Now they probably already informed you of this when you hired on buried somewhere in fine print). So, be wearing of writting anything that might embarrass you.
You have an additional element of working for a government agency in that your computer use and communications could be subject to a FOIA (Freedom of Information Act) request. Granted this is usually what community gad flies annoy their mayors and city council with, but tick off a patron and they could do this just to annoy you. I know lots of people who manage city records and this is part of their daily work.
What that really means, is it covers the city/library if you do anything embarrassing - they can fire you right away pointing to their policy saving face with the community.
Personaly, I'm thinking a Treo might be a good investment for myself sometime in the future
