http://docs.mongodb.org/manual/release-notes/2.6/#aggregation-operation-may-return-a-cursor

"The aggregate may now return a cursor rather than a result document. "
Should probably say "The aggregate command may now.."

Also, it needs to be cleared that the aggregate shell helper RETURNS a cursor. Not "may" or "can", it returns a cursor now, hardcoded.

See also DOCS-2061 (aggregateCursor() helper as been removed)