Like milk, when data is stored in our refrigerated data storage facilities it should have an expiration date. Imagine a milk that degraded in your fridge and disappeared after the expiration date. The perfect solution to taking out the trash and having to deal with milk that has gone off.
In the same fashion would it be wonderful to be able to have the ability to submit your information on a form and set an expiration date on them. This way you know that the information will only live for the required time-period set.
From a legal point of view this is very well justified and supported. The Data Protection Act clearly states that data must only be kept for its intended purpose and deleted afterwards. And many organizations do not adhere to it or have very relaxed regulations about when data shall be deleted.
The article by the BBC  also talks about fading data. This is looking at data from another perspective. This is one that data is not deleted but abstracted to other forms of information i.e,generalized.
The current restrictions that I can see are:
- Database engines will need to be engineered in such a way to facilitate the storage of such information
- Will operating systems need to implement the expiration of data?
- What happens if someone copies the information e.g.backup ? Will the expiration details follow the information?
- It is a very data intense exercise if data is to be transform into an abstract set of the original data, then what are the rules, inputs and outputs that define this process. This can be very tedious and I would imagine very few organizations would implement it unless it was automated in some way.
There are probably many more, certainly I can imagine a number of people who would love this feature of having data that expires. We must be careful though because once it is gone then there will be no way to retrieve it again and in some very rare occasions forgotten information can be handy.
 – Harold van Heerde – http://www.vanheerde.eu/
 – Fading data could improve privacy – http://news.bbc.co.uk/1/hi/technology/10324209.stm