My hat is off to them for pushing the envelope a bit.
But a language is not just a language. It is also the basis of a larger culture and network of engineers and the goodwill between them. php is far more than just a language, it's the good will that I go for, that has kept so many developers with it.
I do not trust facebook anywhere near as much as I trust php. So no, I won't be converting my code.
For one, I don't like the name 'hack'. I think it shows lack of imagination, disrespect, and youthful arrogance.
What I hope to see come out of this, is to spur the php developers a bit. .. to shakeup those unwilling to take bold steps forward.