"A second stimulus package should 'emphasize investment in infrastructure,' such as roads, bridges and other construction, as well as alternative energy projects"
I couldn't agree more. I'd extend that 'infrastructure' to retooling existing non-green infrastructure into green infrastructure such as providing:
1. direct financial assistance to State's with business plans for mass transit. This would help 2 issues: some State's financial problems and their need for revamped transportation options
2. government subsidization/investment in alternative fuel stations and productive capacity along the lines of Obama's energy plan to support a plethora of alternative energies
That along with general spending on regular infrastructure is a good second stimulus I would support.
I would note that this should NOT be the only spending regarding Obama's overall environmental strategy. The long-run strategy should include research and oversight and strategizing on exactly what kinds of green initiatives make the most sense for the US to pursue. It's always best to have a plan first, then start putting money where it matters.