I'm chuffed to report that the front page of plone.org and the /sponsors page (plone.org/sponsors) no longer require manual updates to the theme 
They now do a query of FoundationSponsor objects to obtain the logo, sponsor names, and relevant URLs.
The usual Dublin Core metadata (effective, expiry dates) apply too. Very cool 
This means it's even easier now for you to become a Foundation sponsor!
The relevant code changes are at
- https://github.com/plone/ploneorg.core/pull/240
- https://github.com/plone/ploneorg.core/pull/241
- https://github.com/plone/ploneorg.theme/pull/13
Thanks to @sneridagh for his guidance!
The home page is a Dexterity content type. The sponsors page is themed via Diazo, so the new queries are implemented as browser views.