If you look at
UnTaran's profile, near the top at the left with "Username", "Score", etc., UnTaran's last activity is listed as "Last Activity October 29, 2010 - 21:58:42". However, if you scroll down to the "UnTaran`s latest activites" table the latest activity is listed as "November 25, 2010 - 23:14:54 Gained 0.66% on MiBs Challenges (117 points)". My table is also slightly out of sync.
It looks like maybe the "Last Activity Table" table only tracks challenge updates and the "Last Activity" date at the top only tracks WeChall activity-- logins and forum posting(?). If so, it seems odd to have two different pieces of information labeled essentially the same thing.