Jani Hartikainen has posted some of his opinions about code commenting in a response to this post from James Carr claiming that code comments on fresh code is a bad idea.

James puts it quite well: When you write comments, it would be much better idea to just talk with your coworkers about it. He uses "excuses" as an example - code which does something that you need to explain, or says something like "Here we do X but we should really do Y" While I partially agree - if you're not sure which approach you should use, or whether your approach is correct, talking with your coworkers is definitely a good idea.

Jani talks a bit about what he considers good and bad commenting - non-redundant, descriptive and sometimes difficult to remember to do correctly.