So if I fix a bug, and now Pharo 1.3 will have to load package.pharo13.3 and Squeak package.squeak43.5, I would declare 1.3.1 in my config with the new packages. Does that sound right?
Yep, sounds right. What if you only need the bug fix in the Pharo version and not the Squeak one? The package becomes 1.3.1 in Squeak but is identical to 1.3.0. No big deal I guess... My main concern at the moment is that a MetacelloConfig is always modifiable. It is tempting to fix a version that is already distributed and thus confuse everyone. A release should maybe be a complete new entity (and not editable) hosted somewhere else than in the code repository. The Fuel gsoc would probably help a lot for that. We can maybe imagine something à la Ruby gems?