Some great conversation on Louis Gray's Buzz, including a comment by the 23andMe co-founder:
"This is one of the most thorough and accurate summaries I've seen (I'm the co-founder of 23andMe). One small point...the testing technology 23andMe uses is highly accurate, it's just the interpretation of what the datapoints means which is, in some cases, early and subject to revision (this would be equally true if you sequenced the entire genome vs. genotyping, which is the SNP-based technique used by 23andMe)."
It's not - it was an option during sign up. It's just useful in case they have new features in the future and need to reanalyze your sample you won't need to send in a saliva sample again.
"This is one of the most thorough and accurate summaries I've seen (I'm the co-founder of 23andMe). One small point...the testing technology 23andMe uses is highly accurate, it's just the interpretation of what the datapoints means which is, in some cases, early and subject to revision (this would be equally true if you sequenced the entire genome vs. genotyping, which is the SNP-based technique used by 23andMe)."
http://www.google.com/buzz/louisgray/ZMEciBEeakh/Review-23an...