Nasty Old Cells
I really don't think we can ride the fence on this anymore. You can not say you are for stem cell research but that you feel we should use the stem cells we already have without producing new stocks. As cells divide, they accumulate errors. When undergraduate, Joe Schmoe, forgets to check the incubator and lets the cells get a little anoxic, genomes are damaged. When Chatty Cathy lab tech or graduate student is working with the cells, she may accidently sneeze into them, causing havoc. Cells with genomic alterations are no longer doing the same things that our normal cells are and are thus inappropriate for studying and definitely not good for transplantation. At some point, these cells are going to be nasty-little-cancer tablets waiting to happen.
I don't believe we are going to see Parkinson's cured tomorrow with this technology, nor do I believe we will reverse Alzheimer's anytime soon. I know many people who are working with stem cells, and their data are as promising (or not) as you want them to appear--sometimes it works other times, not so much. I do believe we need to think about these issues now for when we are ready for the technology transfer to happen, though. If you are against stem cell research that's fine--just don't ride the fence like our mindless, robotic politicians.