All the novels have been released as fan translations. Currently there's 9 Volumes out.
[mod edit: details about the novels removed; this can be discussed in the novel thread]
Give everything that's going on, it seems likely that Volume 1-4 will be adapted for the anime, to give time for the rest of the story to unfold - I'm quite sure the author and the production team don't want a repeat of the Season 3 Rurouni Kenshin fiasco (where season 1 (Tokyo) was good, S2 (Kyoto Arc) was
fucking awesome and S3 was horrible.)
Edit: Rewatching the trailer, Kayaba's voice sounded really familliar, so I looked up the cast list on ANN. Turns out he's voiced by Koichi Yamadera, aka Kaji, aka Togusa, aka Briareros, aka a great many leading men. Listening to his voice and how he addresses the players, I get a vibe of Togusa channelling some of the more hammy villains from Ghost in the Shell.
...also, from some angles, Cline's look
really reminds me of Solid Snake.