A novel for Splinter Cell: Conviction is coming from author David Michaels, according to an Amazon listing for the book (which will apparently be released at the budget price of $10). It will be released on October 27th, 2009.
Michaels is actually a pseudonym, his real name is Grant Blackwood. Previous credits of Blackwood include the two novels Checkmate and Fallout (released in 2006 and 2007 respectively).
Conviction is the first Splinter Cell novel that will use the same title as the game, and thus it will also follow the same events that players will take part in virtually.
It also seems that the same author is working on another Splinter Cell novel called “Endgame” which is scheduled for release on November 24th, 2009. This second title will apparently “complete” the storyline of the Splinter Cell series.