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Peekay, XOOPS 2.6.0 will be a cleaned-up, refactored, and streamlined XOOPS, i.e. all PHP 4 code will be removed, as well as code from old versions of XOOPS, and there will be more consistency throughout the Core.
This will be best quality XOOPS ever. Even if this is only a pre-Alpha version, there is at the moment not a single error notice when using E_STRICT on PHP 5.4, which we cannot say about 2.5.5 under E_STRICT. Trabis did a fantastic job with cleaning up the 2.6.0 code.
ForMuss also added Twitter's Bootstrap, which is very cool! And Mage is working on extracting features like Smilies, Avatar and others, and making them independent plugins, so the Core becomes more "lean & mean".
Once we are done with 2.6.0 and is working properly, we'll start adding new features to it.
I encourage you to download the pre-Alpha version from SourceForge SVN and take a look, so you'll have a better perspective.