A very wise man once told me 'dont post what you dont want stolen'
Personally, I am not 'too' worried over the new legislation. 95% of my photographic income is from weddings, portraits and commissioned work, the other 5% is from picture sales, pictures that I have generally created for my enjoyment.
I think where problems may occur for allot of people is if/when their work is used out of its intended context, this could have an adverse effect on their reputation and put people off.
In respects of protecting your images, like Kurt said, I would post as small as possible without taking away the enjoyment factor of your images. I would make sure EXIF/Meta data is embedded in all images and that the sites I uploaded them to preserved this data. I generally watermark my images, the watermark normally includes a web link and or email address, I also hide a very small signature in some of my images.
At the end of the day through, if someone wants to use an image, they will. With the power of Photoshop these days, watermarks can be cloned out with easy or the image can simply be cropped. Large print/online organisations have done and will continue to use pictures without prior permission to meet the ever shrinking time demands of modern age. As we have seen in the UK, consequences, if any are faced later and generally amount to a slapped wrist and a small amount of compensation if anything at all.