This just popped up in the news although I’m not sure when it actually became available.  Business Facilities: The Location Advisor has published online its 2011 Incentives Guide: A comprehensive guide to state incentives offered throughout the U.S.
I can’t vouch for the publication’s accuracy (that’s not my job), but I am definitely impressed with how much information they’ve gathered into one place.  They’ve included brief description of hiring and investment incentives for each state.  Click through (above) and check it out.