Lukas Smith has a new post today about what he sees as an important part of PHP (or really most open source projects) - a predictable release cycle. It centers around the recent proposal to introduce the Zend Optimizer+ into the core and how it seems to be causing a delay with 5.5 (maybe up to 2 months).

What troubles me though is that its being proposed very late in the game for PHP 5.5, therefore causing a likely delay of 5.5 of at least about 2 months in the best case scenario if it were included. The other option of including it in 5.6 does not seem to be as popular at this point. This saddens me quite a bit since I believe that predictable release cycles would carry several advantages

He points out some things that come along with having predicability around the software releases like developers knowing when/if their changes will make it into the next release. It also makes it easier for end users to plan their releases of their own software, knowing when they'll be getting a feature. In this particular case, though, he doesn't quite understand the delay as the Zend Optimizer+ isn't a change to core, it's an addition:

What is even stranger for this case is that we are just talking about an extension here. Its not a language feature, there is no engine level integration. So even if its not added to core, people can easily get Optimizer+ via PECL. So in this case we are not talking about people having to wait another 10-11 months. Don't get me wrong I think getting an opcode cache into core is awesome, but the reality is that shared host users will probably still not have access to it [...] and the rest can still get it, albeit with a bit more effort.