Mark McGwire was an amazing athlete who fell to temptation of using steroids (to help with recovering from injury, or so he says). This bit of information is not news since most people who watched him or looked at his stats had huge suspicions that he was in fact a user. This news would be classified under the "No $#!t" file.
From what I remember McGwire never lied about being a user. At Congress he said he wasn't there to talk about the past which made him look like a coward. But to his credit he didn't lie (unlike the famous Palmeiro scene).
There have been a list of guys who have admitted to using performance enhancing drugs, but that list is small compared to those who are still under suspicion or who have been caught but blamed it on someone else (Manny Ramirez). Now we can add McGwire to the not-so-bad list.
The typical American sports fan (and American in general) want people to be upfront about their mistakes, especially when you are caught. Barry Bonds, Sammy Sosa, Roger Clemens, a host of other baseball players (Pete Rose), and Tiger Woods could all take a page out of McGwire's book. Maybe don't hide out for as long as McGwire did, but either way come clean about your dirt.
The truth really does set you free.