I ran across an interesting article last month. A survey was recently conducted in which IT workers were asked whether they use "their IT privileges to gain access to employees' confidential data". One in three admitted to doing so. Have a look at
http://windowsitpro.com/article/articleid/99515/do-you-snoop.html for a little more detail. If a third of them are admitting to it you would think the number actually doing it would be somewhat higher.
It is hard to provide a tech solution for privacy from your system administrator. It can be done but it is a lot easier and cheaper just to trust your tech. It is what we do at my employer and my clients. All these places do have personnel records, for example, and I should not have access to them, but I do. I don't even need to be in the building to see any of it, as long as it is an electronic file.
But look at it from the tech's side. If for some reason the trust fades, then the tech is automatically a suspect simply because he has had access to the confidential information. So it is not a very good situation for the tech either. I don't anticipate providing any good solution to this though anytime soon.
Sorry there is not much of a tip here but I thought you would enjoy hearing about the high moral standards of the average tech these days. Truth be told, I suspect this would be accurate for the population at large, if they had similar access to your information.
Note to my own employer and clients: My lips are sealed.