I long ago learned that if you want to get development work done then always use the distro's own version of PHP, Apache, etc, rather than compiling your own version. Otherwise every upgrade due to a security or bug fix requires you to first realize the need (costs time keeping up with the study) and then do something about it (costs time). Time is money; not spending the time is insecure. So I outsource all of that to the experts at my distro or ISP.
Consequences are that my code avoids using the latest feature, and tries to work on as wide a set of versions as possible. PHP 5.0.0 was released in July 2004 yet at the start of this year two of my clients were still using php 4. One of them was still using php 4.2. (They've both upgraded this year; one because they moved to a new ISP, the other because we were troubleshooting code and running out of ideas, and wondered if moving to php 5 might magically fix it.)
Which is a long-winded introduction to say that PHP 6 will be out before long, and I'm very unexcited. It brings native unicode; but the mbstring extension already did the job fine. It removes bad stuff that was already deprecated, but I didn't use it anyway.
This article made me concerned it may turn out to be a negative experience overall, rather than a neutral one:
It says PHP4-style classes are disappearing. Yet they work fine in PHP 5, and E_STRICT has not been complaining if I've not explicitly written "public". Of even more concern is php 5.3 apparently brings in this change too?
However, it turns out this was just a poor Linux Magazine article. What is being removed in php 6 is "ZE1 compatability mode" (see the php manual description); it had defaulted to off, and only affected the way objects were copied/compared. The "php 4" example Linux Magazine show is valid php 5 code, and (as far as I can tell) will be valid php 6 code too.
So that was a red herring. But I'm also bothered how (string) works for binary strings in php 5, but will need to be changed to (binary) for php 6 - that is a very annoying change for anyone storing binary data in strings (disabling unicode is not an option if you also need to store UTF-8 in other strings)!