Intellectual property 101
michael_dorfman: I'm not a lawyer, but I just went through a round with one on a similar issue.  In my jurisdiction (which is outside the US) the principle was that code was protected, and ideas were not (unless patented), BUT if I went ahead and built a product that was suitably similar to one I had worked on before under an employment contract, the burden of proof would be on me to prove that I did not copy the code (and thus it was a good idea to throw in some novel features, and use a different programming language/framework/platform).Still: spend the bucks and ask a lawyer, if the issue is relevant to you.  Better to have too much legal advice than too little (believe you me.)