I'm a bit of a skeptic. The tax credit is a nice idea but will more than likely have very little effect. It is expensive to hire a person and keep him working, slicing a couple bucks off that expense in the form of a tax credit will do little in the scheme of things. If the credit is anything like the previous ones it's only be good for about a year or less which makes it less appealing.
The public works projects will do the same thing it did last time. Not much. And once you expand that past roads/bridges to facilities such as schools you also put a greater burden on local government which will have to staff and maintain the facilities. Local government is already having major budget issues.
I hope I'm wrong... but this new stimulus seems to be following the old one, which ran $700-800 billion and kept us at 9.2% unemployment.