Pretty much everything is already known about the LS3 now, but I figured it doesn't hurt to have it listed in one easy to find location. 
Some LS3 specs:
6.2L V8
376 cubic inches
Bore: 4.065"
Stroke: 3.622"
Compression ratio: 10.7:1
Horsepower: [email protected]
Torque: [email protected]
Same fuel injectors as the LS7.
Heads are LS7/L92 style, which flow awesome.
2.00-inch intake vales, 1.60-inch exhaust vales.
Stock cam .551 lift
Redline: 6600rpm
Some LS3 specs:
6.2L V8
376 cubic inches
Bore: 4.065"
Stroke: 3.622"
Compression ratio: 10.7:1
Horsepower: [email protected]
Torque: [email protected]
Same fuel injectors as the LS7.
Heads are LS7/L92 style, which flow awesome.
2.00-inch intake vales, 1.60-inch exhaust vales.
Stock cam .551 lift
Redline: 6600rpm