I am incredibly excited about this. I am an absolutely huge fan of the novels and the games -- seriously, some of the most interesting story and lore elements.
I implore anyone who hasn't, to go read the books and read up on the D'ni culture and history. It's very awesome.
Also go play the game, they are some of the best adventure games, with the exception of Myst 5 (which would have been awesome if Cyan wasn't forced to rush development by UbiSoft). Uru is a fairly awesome concept as well (it's a shame the online version is being shut down), but for me it's not as immersive as the original series.
I'd have to say Riven and Revelations are my favourite Myst games. Though they are all beautiful games.
I believe the movie will be based on the novels, though not much has been revealed yet (other than for the last 4 years Mysteria have been working with Cyan to get things in motion for the movie). More is going to be revealed soon though!
Myst - The Motion Picture - Production Journal