So what can you do about it?
Well the first response to this issue is usually "don't post what you can't afford to be copied" and this is a logical one. But as we know, content is given away all the time on the web and is a viable revenue model.... provided of course you can monetise your traffic effectively (e.g. by advertising) or get something back for it (e.g. this blog, which I do for free to keep me abreast of the latest online communication methods & technologies).
But there is also a serious reason for every site to worry about copied content and this is that search engines such as Google take a negative view of duplicated content. Therefore should someone copy large sections of your site for instant content on theirs, this may negatively affect your organic positioning (as the search engines could think you are trying to create duplicate sites to spoof them).
Note: This would have to be a lot of copy and Google actually tries to avoid this action:
In the rare cases in which Google perceives that duplicate content may be shown
with intent to manipulate our rankings and deceive our users, we'll also make appropriate adjustments in the indexing and ranking of the sites involved.
Note: other ways include..
1. Embed protected content in Flash :
But although Google can at least partially index this content now, doing this still sigificantly hampers your SEO efforts.
2. Utilise screen scraping avoidance techniques
If you wanted to completely stop any indexing of your content then you could get it placed within an image. This can be done using dynamic image render technologies