I noticed this new version of Zen photo still uses the ereg function which is deprecated in PHP 5.3 and will be removed in 6. So technically Zen photo requires PHP 4.4.8 > 5.3 (bigger than 4.4.8 but smaller than 5.3).
Will the next version support 5.3+ ?

Zenphoto does support PHP 5.3 (although not much providers have that right now as it is quite new) as these deprecated warnings do not mean that the functions are not here anymore or do not work. They will be removed with PHP 6, until then they work fine.

Anyway, the coming 1.2.7 release will hopefully have removed all ereg function usages. Please try the nightly build to help find anything we might have missed.