When Bush left office, we knew many things would change. Surely enough, within the first few months in office, Obama outlined new provisions for stem cell research; he repealed Bush's ban on funding research and generally made it clear that he supports the cause and would do his best to expand it.
A federal judge passed an injunction on Obama's efforts today, effectively halting all federal funding to stem cell research. Judge Royce Lamberth ruled in favor of the plaintiff Nightlight Christian Adoptions, who argued that the destruction of human embryos during research makes fewer embryos available for adoption (Christian adoption, presumably).
Federal law explicitly forbids use of taxpayer dollars to destroy a human embryo — and culling stem cells from an embryo does destroy the embryo. However, once created, these batches of stem cells, or lines, can reproduce indefinitely in lab dishes.