Thanks to the Wikipedia article for the image of a colony of embryonic stem cells, from the H9 cell line
President Obama on Monday, March 9, 2009 authorized government funding to support research on stem cells newly harvested from human embryos.
Embryonic stem cells come from an early stage human embryo called a blastocyst, a stage reached 4 to 5 days after fertilization. Initially there are 50 to 150 individual cells.
Human embryonic stem cells were "discovered" in 1998 by privately funded researchers. In 1999 President Clinton authorized federal funding as long as no human embryos were destroyed. In 2001 President Bush restricted research to existing stem cell lines. President Obama rescinded the previous administration's rules.
President Obama also signed the appropriations bill on March 11 which explicitly bans research that might injure, destroy, or place at risk any human embryos.
Ethically I certainly understand the concern.
I suspect it will open a door best left closed.