i heard pc cast say in an interview that the series is signed in a deal of twelve books so there will be twelve books in all in the entire series. however im not sure of the titles of the coming up books.
If I remember right, there's only to be 12 books. I don't know the names sadly. When book 10 comes out in October it should say what the next book is going to be called. Then there's the House of Night side story about neferet coming out in february.
There are going to be 12 books
in order they are:
12. Redeemed(not coming out till 2014)
and the novellas are:
The Fledgling Handbook 101