Extend the packagehistory.bbclass to dump out data on package sizes, their contents, their dependencies, their build time and other information. The objective is to save this data so changes can be detected. One idea is we could save the data in the form of a git repository. The existing OE testlab code has some similar functionality.
I have posted the initial implementation of this as an RFC patch for review on the openembedded-core mailing list; however that mailing list seems to be having trouble at the moment. In the mean time there is an oe-core tree with the change here: http://cgit.openembedded.org/openembedded-core-contrib/log/?h=paule/packagehistory
Thanks for Paul's suggestion on how to test Package History. Test Plan is ready for the feature.
Richard has asked me to integrate image history into this as well, so I'm currently working on integrating the functionality from testlab.bbclass in meta-oe in a packaging system agnostic way (testlab currently only supports ipk). This will increase time to implement but I hope to have something working in the next few days.
buildhistory.bbclass, which integrates testlab and package history functionality, has been posted as an RFC: http://lists.linuxtogo.org/pipermail/openembedded-core/2011-December/013699.html
This functionality has now been merged in revisions 6ba6f4a6f744895741c82f93756439292f563bf6 and ef1834ea4ce50087b0ab081d8fee6615743120b9 (and are also in the 1.2_M1 branch).
I tested buildhistory feature with 1.2 M1 branch, with commit b9d3a5224c7f76f273d5919a88b7460d35ad2574. It could work.