Is there a way to backup everything in an app-engine blobstore?
In Java, you would instantiate a BlobInfoFactory and use BlobInfoFactory.queryBlobInfos. 
Then for each blob, you would run BlobstoreService.serve(...) with the BlobKeys returned from the BlobInfos.  You still might end up with broken entity relationships - there's no way to guarantee each blob will end up with the same key it was originally loaded with.  You'll have to account for this in your application.
bulkloader.py is very handy. 
But as far as I can tell it doesn't appear to fetch items from the blobstore, so you can be left with broken entity relationships if you needed to dump/restore your application.
Does anyone know a method for completely backing up their data from app-engine including blobstore data?