The WordPress blogs of some of my friends were generating feeds with a CDATA tag in the description field. Blagg let this tag get through into the aggregator post, resulting in these posts not showing any description body. Oh, the tragedy!
The small change needed to fix this can be found here. Astute readers will see, in the lines of this patch, that Perl really does suck.
At some stage, I will have to see about a possible migration to wordpress.