Holy fucking shit. http://www.wired.co.uk/article/us-gov-lift-ban-part-human-part-animal-embryo-development
Basically, the practice has been banned in the US, and now it really seems like that ban is about to be lifted.
The arguments for lifting the ban are pretty much about helping us deal with all sorts of diseases and medical conditions:
And the arguments against are, well, pretty much as expected:
What do I personally think?
I think this is actually a healthy step to take - it will eventually help us learn much much more about our body, and maybe even discover some pretty interesting stuff in the process which we couldn't any other way.
On the other hand, this could produce some pretty insane results.