My provost just sent some of my colleagues a link to this article on games and literacy:

But doubtful teachers and literacy experts question how effective it
is to use an overwhelmingly visual medium to connect youngsters to the
written word. They suggest that while a handful of players might be
motivated to pick up a book, many more will skip the text and go
straight to the game. Others suggest that video games detract from the
experience of being wholly immersed in a book.

Some researchers,
though, say that even when children don’t read much text, they are
picking up skills that can help them thrive in a visually oriented
digital world. And some educational experts suggest that video games
still stimulate reading in blogs and strategy guides for players.

To
be sure, some of the experiments pairing electronic games with books
will be little more than marketing gimmicks. But publishers and authors
suggest that some projects may push creative boundaries, helping to
extend storytelling beyond the traditional covers of a book. (Motoko Rich, NYT)