Often dates are extremely relevant, for example a 10 year old hardware review won't be as relevant as a new one. On the other hand, blogs don:t have to be static, some programing technique might still be relevant, but need to be updated for a new version of the language.

Solution: put a "first published" and a "last updated" date, or use a wiki that makes the revisions available online and a way to link to the different revisions.