、？
Now then, does everyone know the anime called 'Mai-HiME'?
Literal
Well-well, everyone [topic-は] Mai-Hime [called-という] anime [object-を] know-[resulting state-ている][copula-でしょう][question-か]?
Blog/forum register. さてさて is a doubled form of さて 'now then, well,' used as an attention-grabbing interjection at the start of a new topic — characteristic of blog writing. 舞姫 (Mai-Hime) is the title of a 2004 anime (also the title of an 1890 Mori Ōgai short story, but context points to the anime). ~という (as a modifier) means 'called, named.' 知っているでしょうか 'I wonder if you know' is a tentative form of the knowledge question, softer than the plain 知っていますか.