Strange, my country (Poland) has a law that allows reverse engineering to allow given software to work on given hardware. If (and only if) consumer has bought given software.

So e.g. I could reverse engineer MS Word to make it work on Linux and that is within my legal right, any EULA prohibiting that is void.

Same probably applies for jailbreaking - all withing legal right of customer.

I think there is something in EU law also about that, considering SAS Institute Inc. versus World Programming Ltd.