Notes for the Google "hack-a-thon" tomorrow. Hopefully I'll get some interesting responses!
1) Image upload/resizing: db.BlobProperty will store it, but resizing not possible?
2) Full-text Search: Doable, but limited. See google.appengine.ext.search.SearchableModel
3) Schema updates: how is this handled? It appears that there's zero support for schema migration/rollback. Something like RoR's ActiveRecordMigration would rock.
4) How about a "Certified Developer" program? Give small-time developers an incentive to learn your technology stack, and an imprimatur when they do, to help them bring other parties to your platform faster. (think: MCSE and similar programs by Sun, Cisco, Oracle, Apple, Red Hat, Ubuntu)
5) Batch processing? Will we get Python MapReduce with access to the App Engine (BigTable) datastore? :-)