JS_Harris - 11:39 am on Feb 8, 2010 (gmt 0)
Tedster is right, link value does fade and the reason why is simple. A good majority of your backlinks will be on pages within other sites that are naturally sinking in importance. An article written 3 years ago with a link to your site may be buried back on page 488 of their archives offering very little pr type value.
Checking how recent links are is important but checking WHERE those links are is equally important. To keep it simple just start at the index page and count how many clicks it takes to reach that link. Shallow, or on a page linked from the index, is desirable.