There is now a serious alternative to lua: Jx9 which uses a syntax similar to C and JavaScript and is being used in many commercial games.
http://jx9.symisc.net/
I think the Jx9 license is correct and acceptable for open source softwares since many open source projects embed BerkeleyDB which use this kind of license.
PHP has the wind in its sails or what? last month i got pointed to PH7 ( http://ph7.symisc.net/quick_intro.html ) which is an embeddable PHP interpreter (bytecode compiler + VM) for C/C++/Objective C host applications (amazing piece of work) and now I'm investigating this stuff.
Start with the PH7 engine which is an open source embedded PHP engine (useful tool to add web interfaces to your C/C++ application). It have a very nice and clean documentation and readable code.
Here is the URL: http://ph7.symisc.net/