The results on a dyno vary depending on climate, air density, and other factors, but I see that the 09 has 155hp and 150lbs torque according to Edmunds.com. I would imagine they really didnt change much between 07-09.
I have seen a few LS's carrying the power doors/windows. I would imagine 115-120WHP is average on the car. Its not a whole heck of power, but you also need to put into perspective, that it gets up to 37Hwy MPG which is very impressive.
2009 Cobalt LS XFE U74
Mods: K&N Typhoon Intake, Option Cat-Back Exhaust, Cosmo Short shifter, Maxxim Ahead 17X7's, MPx shorty antenna, FE5 Strut/shocks, Tein S Techs, Moog endlinks, Moog spring seaters, ZZP shorty header, LSJ downpipe, LNF front grille