For quite some time we have stated that there is no official support for PHP 5 and MySQL 5 on dotProject. This position has been rather controversial and many people have been rather vociferous in their opinions (mostly negative) about this subject. I'll try and cover both the reasons and the future as I see it.
PHP 5 is starting to become available on hosted sites. It is by no means ubiquitous, but it is happening. Unfortunately there are some very big differences between PHP 4 and 5. This has meant a lot of going over and refactoring code. We are also in the situation where some of the libraries we use (jpgraph being the most obvious) have now split support into PHP 4 and PHP 5 versions. You have to pick the right one or it won't work. This is going to make it increasingly difficult to provide a unified version that will work on both platforms, and so at some point we either have to provide two versions, or we drop support for PHP 4. Given that most of our users are on hosted sites and most of those don't yet support PHP 5, the decision gets even harder.
Some developers are making plans to provide features that make use of PHP 5 in dotProject and only supply them to their own customers. Personally I see this as a dangerous precedent to set and one that has already bitten a number of projects. Not so much the PHP 5 features, but the "pay up and you get the shiny version, don't pay and you get the crappy version" mentality. This is starting to pervade open source companies as they struggle with the concepts and new business models required to actually make a living from open source. The successful companies, like Red Hat, take a somewhat opposite viewpoint, which is that if you are prepared to take on untested and cutting edge features, you get it for nothing (Fedora), but if you want support and solidly tested and secure features, you need to pay for it (RHEL). This is the model I always saw as being the best for dotProject. But hey, people need to eat.
MySQL 5 is a more interesting proposition. From what I can see it has even less penetration than PHP 5, yet previous versions are no longer under support. I'd very much like to make use of some of the newer features of MySQL 5 (and of PHP 5 for that matter), but unless the situation changes on hosting services, I don't see it happening any time soon. I guess part of the problem is the releases of operating system they are running, which up until recently packaged PHP 5, but only version 4.1 of MySQL. Upgrading an OS is a big decision to take, so it will happen, but it will take time.
So, gazing at my crystal ball I see the standard dotProject version supplying the jpgraph library separately, and allowing you to get either the 4 or 5 version, rather than bundling it. This will allow us to continue to support both 4 and 5 until the hosting situation has clarified. Looking further, I see that we will drop support for version 4 of both PHP and MySQL, and start to use the enhanced features that the new versions offer. Looking further again, I see a RedHat style subscription service for automating security updates and installing "certified" add-ons.
Mind you I am not offering timelines here, nor am I offering guarantees, after all it is a crystal ball, and may be a bit fogged.