They were released after her 10 year anniversary, a year after Heart Station. and what cube said, except vice versa. Ten is a collection of her interviews and an autobiography. It also includes lots of wonderful photos. Sen is her blog posts.

There were also goodies you could win for purchasing both Ten and Sen. 25 Ten Original Hard Disk. 25 Sen Original Hard Disk. 1000 Ten & Sen USB Memory Stick. I won one of those memory sticks. It looks exactly like the cover of the books. Ten on one side, Sen on the other.