In a link from PHPEverywhere, there's an interview with Rasmus Lerdorf, the one who started it all.

While the entire interview is an interesting read, there are two questions that John Lim notes - the answers to these two questions: "What about PHP 6?" and "Would Parrot replace Zend or would they work together?". Of course, you'll have to read the interview to find out the answers, but it's worth the time.

The only concerns expressed are "how would this affect Zend?" I don't think anyone really knows at this stage. This could allow Zend to target a larger market, but it would obsolete quite a number of their existing products.