There is a provision in NCLB that forbids the government from testing homeschoolers under NCLB. Some states have tried to mandate it. If a school does, however, it loses federal aid. Those wiley people from Homeschool Legal Defense Association made sure of that.
Now, under Obama’s administration, I don’t know if that has been changed or if the fine folks at his Education Department just haven’t thought of it yet.
It hasn’t changed. PISA, however, isn’t part of NCLB. Participation would have to be voluntary by homeschoolers, which isn’t going to happen.