两个英文句子的语法分析，也就是这是定语从句还是宾语从句？

ICT is not only changing the nature of work,it is also starting to change where that work is done.
"where that work is done" 是一个宾语从句，做change的宾语。
这个宾语从句由特殊疑问句“where is that work done？”充当，特殊疑问句单独使用要is要提前，但特殊疑问句做从句时，词序改为正常顺序。因此为“where that work is done。”
整个句子翻译：ICT不但正在改变工作的性质，而且开始转变工作的地点。

Companies are starting to look at the possibilities of teleworking，or telecommuting，where staff work at home or from a telecentre.
“where staff work at home or from telecentre” 可以看做是“the possibility of teleworking or telecommuting”这个名字短语的非限制性定语从句。

你的理解有些偏差。独立的句子，就是“Staff work at home or from a telecetre." 就等于”thepossibility of teleworking or telecommuting“或是对其的解释。