What's up with 5.1x beta

[Ed Reed]

Does anyone have an explanation as to why it's taking so long for an official 
release of version 5.1? Is it me or does it seem like 5.1 is taking a lot 
longer to be released. I don't remember previous versions having 20 beta revs 
before an official release. Is there a real date available for an official 
release?