Th3rd World Publishing is going to be releasing the Mortal Instruments as a series of comic books. They will be released first as monthly installments and then bound together into graphic novels (one per book) and released in bookstores. The release dates haven’t been announced yet, though I do know the comics will begin releasing in winter. As of now they will be available only in North America. You can read more about it here and see some sketches of the characters here and here !
The Infernal Devices: Yen Press will be releasing The Infernal Devices as a manga series beginning in winter, 2012. You can see the beautiful cover of the first installment below.