Ask HN: What's the standard approach to IP clauses in employment contracts?

As one of the many students starting to consider offers for after graduation, I have some questions about the industry standards regarding certain clauses I've seen in a few contracts. (I'm considering various consulting positions, but am also an active developer on multiple open-source projects.)

These IP clauses usually say something to the effect of "Any and all writings, inventions, improvements, processes, procedures, and/or techniques which I may make, conceive, discover or develop, during the term of employment with <firm> ... shall be the sole and exclusive property of <firm>."

Is this normal / Do people normally submit to this? The projects I'm involved in are GPL (which should mean tough-luck for the employer), but I don't want to give up any ideas/projects I might have in the near future.<p>Can anyone give me some insight?