I don't know! I never switched over to anything else after Delicious became unusable so I know nothing about how any of those work. It would be nice, though. (And I did not know you had an automated system set up! Are your non-fic linkspams automated, too?)

How integrated to Wordpress is the Diigo-to-wordpress thingy? I bet it would be possible to hack something together that would let you repurpose the post-by-email system to do it, if nothing else... I'm pretty sure that's how people use LoudTwitter on DW.