I just read in the November 2006 issue of GM Hightech Performance magazine that GM Performance Parts will be releasing a new LSX block. The block (part # 19166454) will still be 6 bolt mains and wet sump lubrication. It will be an iron block capable of withstanding 2500 horsepower. The deck height and cylinder bores will support up to 480 cubic inch and the estimated cost is $2500.
GMPP also states that LSX heads, intakes, and crate engines will follow.

 

There's a nice thread about it on tech. Including pics too Also word of an aluminum version in the future!