Remember Dolly? well apparently Dolly has developed athritis at a very young age, raising fears about the whole cloning process. The develpement process is far ahead of consequences.
About human cloning, i would not be surprised if this has been done already, we all know that Genomic reaseachers always drop the bombshell after the fact! Infact a secret firm in Nebraska is currently advancing to produce a replacement copy of a 10 month old baby that died...and guess when they expect the clone to be born? read this..
http://www.globalchange.com/clonaid.htm