All the way up until I want to say version 1.0 of zenphoto, that was how the default themes, and zenphoto were coded. People were having problems with it not working under certian configurations and this then changed.. Some remnants still linger behind... Zenphoto itself should not have this problem anymore. It should only be themes,
A simple find and replace should take care of the problem...
It's the php_short_tags directive -- we did indeed stop using it as of 1.0.2, and fixed all the old code as of 1.0.3, but we can't control third-party theme releases unfortunately. I will definitely make sure all released ZP code doesn't have short tags, and I'll put a notice in the theme documentation for other developers. Sorry for the inconvenience...