Over at Jay Greene's blog he provides an update and a very detailed list of the methodologically sound research that shows positive effects of school vouchers on program participants and positive systemic effects for the public school system as a whole.
To summarize nine out of ten gold-standard studies find positive effects for voucher participants:
Here is what I believe is a complete (no cherry-picking) list of analyses taking advantage of random-assignment experiments of the effect of vouchers on participants. As I’ve previously written, 9 of the 10 analyses show significant, positive effects for at least some subgroups of students.
All of them have been published in peer reviewed journals or were subject to outside peer review by the federal government.
As for as systemic effects of voucher programs Dr. Greene concludes that:
The bottom line is that none of the studies of systemic effects from voucher programs find negative effects on student achievement in public schools from voucher competition. The bulk of the evidence both from studies of voucher programs and from variations in existing competition among public schools, supports the conclusion that expanding competition improves student achievement.