First, let me start off by saying that this is a PECL extension, whether that makes it "official" or not depends on your take on that word. The PHP folks aren't going to start demanding that everyone stop using their current framework(s) of choice and switch to yaf. It is just a framework, written as a PHP extension which has been added to PECL. Anyone else could do the same and we'd accept theirs too.
For me, it has negligible impact. I probably will never use it in anger, but it's interesting to look at.
Too late for what? There's still plenty of scope for new frameworks to make a name for themselves.
No. Never. (I hope.) :x
Yep, but only because I follow this type of thing closely.
Sure, the developer himself mentions the connection between the two frameworks. Hopefully people won't get the impression that yaf is zend framework written in C.
Only to poke and prod, to make some "hello world" examples. Just like with any other new framework. (: