disq/facebook-sdk — comment on commit 9b7787e6a9488471f71975f14fd965e2c44b2aaa
File:  line 0
By disq:

It is basic support for Requests 2.0 Efficient feature.

References:
http://developers.facebook.com/blog/post/569/ ("Performance improvements" section)
http://developers.facebook.com/docs/reference/dialogs/requests/ ("Deleting requests" section)