So, by my math the Stamps have clinched into post season.
With 4 wins for the top 3 of the East and 6 games remaining (7 for the Cats), the fact that they all play each-other 1+ times means that one of those teams will record a loss, so there is no way that team can tie the Stamps. So should the Stamps drop each game (not likely to going to happen), then they would still at minimum cross.
This therefore means that a Rider win equates to locking down a spot this weekend. Also, a Esks win and both Als and Argo loss would do the same thing for them (though the Argos don't play this week, but do play the Esks next).
It of course still not technically a clinch yet, but it essentially is in these scenarios....2/3 through the season...wow.