The new license for Fancybox 2 states we cant use this plugin for commercial purposes. I'm a web developer and always promoted this plugin to my costumers. Does this mean I need to find or write a new plugin with a more free license?
Maybe I just don't understand the noncommercial word correct, if so pleas correct me. But what I can find around the internet it's states I cant use a software with this license on a webpage where the business is making money.
Your interpretation of the license is correct (although the usual I'm-not-a-lawyer disclaimer applies). The Creative Commons Non-Commercial licenses are meant to give people free access to a creative work, as long as they don't intend on making money from it.
If - as a webdeveloper - you sell sites to your clients, you're therefor not allowed to use the Fancybox2 plugin using the CC-NC license. Your options are basically:
Addendum: A counter-question to those wondering about the legality of making this plugin commercially available: Could you motivate why you feel this way? The jQuery project is made available under both the MIT and GPL licenses; the MIT license (along with the BSD license) are among the most relaxing licenses in existence. The only demand it places on redistribution is that the copyright notice on the code remains intact, to honor the original author. It's perfectly permissible to ship jQuery as part of software under a different license - even Microsoft redistributes jQuery as part of Visual Studio.