It is true that they are not working on this build. What's not known is whether or not it is a choice or a bug.
In the release notes that many sites have broken NDA and posted it talks about all the features that are not going to the iPhone 4. It doesn't say anything about blur being left out of iPad 3.
This build feels buggy than the previous ones.
Basically, like almost everything with beta, hold your judgement until there is something to judge. We will wait and see.