With the increasing number of information sources on the web today (and, more significantly, the number of non-corporate sources of which blogs and other personal sites make up the vast majority) it seems that more and more often I am interested not only in what is being communicated, but when it was communicated.
Most blogs I come across I find via search (Google, Bing, Yahoo!, etc.) and are typically the response to some question I have. Before I spend a lot of time reading through what may be a lengthy and sometimes fairly technical post, I would like to make sure I check all of the available clues to winnow out items that are probably not relevant. The date of the post is the first thing I look for and I am surprised at how often it is not readily apparent.
Ideally, just as it was in school, the subject and date are somewhere near the top of the page. Not as ideal, but acceptable are those times when the date is located at the bottom of the article. What is unacceptable is when I have to infer the date by checking the timestamps on any associated comments (if there are any).
So, for the sanity of your readers, please choose/design themes which include the date somewhere. Make it understated if you like, but make it available.
Unless, of course, I am the only one who finds this to be a problem. If that's the case I will either suck it up or snap. If some guy in western Kentucky makes the national news because he got a label maker and started covering everything in town with date and time stamps, I guess you'll know how it went.