Hello,
I've just committed the incorporation of "luasocket" by Diego Nehab, see http://www.tecgraf.puc-rio.br/~diego/professional/luasocket/
This allows luatex to browse the web ;-)
What about luacoffee? I'd like LuaTeX to make coffee ;-) But seriously: From looking into the Context source, it seems that this would be used to download modules/packages/files on the fly, just like MikTeX does it. A security consideration, though: There should be an option to disable this module to prevent LuaTeX from playing E.T. (phoning home). Extending the --safer option would not be fine-grained enough, since this option only deals with local accesses, not remote ones. So maybe a --nosocket option. That way, net access can be disabled, but not file access (since --safer also prevents io.open from opening files for writing).
Best wishes, Taco
Jonathan