Unfortunately because of the deluge of non-human members we have been getting on the site (pitching Pharmaceuticals etc.) we have turned on the setting that requires new members to get approved before they can post.
We would prefer to not have to approve new members, and we will make every attempt to approve membership requests as soon as possible.
Ning the host of this site is actively trying to combat Spam, but for now their recommendation is to turn on membership approval. If another solution is found we will turn it back off again.