The courts are likely to extend the law fairly significantly, which should make things clearer, but my own view is that it will not prevent employers monitoring the use of work systems - providing they make it clear that this is what they are doing. If you lay down a policy and then let everyone ignore it you are hoist on your own petard. The issue of transparency is fundamental. That didn't stop them monitoring usage and, in some cases, taking disciplinary action. This lack of definition may guarantee misinterpretation of the policies, leaving both employee and employer on shaky ground.
Moves are afoot on both sides of the Atlantic to regularise the situation.
In America, both Houses of Congress have proposed regulations requiring companies to notify employees if they monitor their computer, internet, or telephone use on the job. It is very easy for employers to assume that it's their equipment and they can do what they like, but you are entitled to some freedom at work. For comparison, it's illegal to break the speed limit and reasonable for the authorities to use speed cameras to monitor what's happening on the roads. But you don't expect to have a police car on your tail all the time. The STUC's Rozanne Foyer agrees.