I stand corrected on this one.
After this posting, I received this e-mail from CIDA (underlining mine):
With reference to your post on your blog, wanted to point out that the standing offer we are seeking through Merx is for work that we are intending to do in the future, beginning this fall.
Work that is being done now is being done via a separate contract through a call up of a Standing Offer offered by Public Works.
Directeur général int | A/Director General
Agence canadienne de développement international | Canadian International
Groupe de travail de l’Afghanistan | Afghanistan Task Force
Thanks for clearing that up.