Mark Shuttleworth announced (a while ago for 11.04) that Canonical would leverage Qt more, and subs equently Qt is found in important parts of Ubuntu like Ubuntu One.

Being a relatively new kid on the block, Unity has its work cut out for outreach to existing developers of both Qt and Gnome/Gtk+ interfaces. Without coordination and documentation the advantages of this delicate balance of legacy interface development and ermerging Unity technology are lost.

In simple terms, this blueprint serves to consider and unify developers' goals and ideas concerning Unity and legacy Qt and Gnome/Gtk+ bindings. Deliverables could include a wiki page for easy to understand development information applicable to both APIs.