Nope. Take a look at most intellectual property agreements out there, and you'll see that employers gain the right to *any* and all "inventions" you may come up with when employed by them.
I count my lucky stars that the company I work for (Mitel, formerly E-Smith) has a proviso in their Agreement that excludes any Open Source development work I do. Quite forward-thinking.
Re: Re: Professional Employees and Works for Hire