It depends on the exact open source license they release it under. I googled around and all I could find was that they would release it under "an open source license".
"The Beta release is comprised of 54 webOS components available as opensource. This brings over 450,000 lines of code released under the Apache 2.0 license, which is one of the most liberal and accepted in the open source community."
And again, IANAL, but I assume the implication is that you can't just grab some code and stick it alongside your app for protection. You are only protected if you actually used the license-giving code in your app in the intended way. So this would not help Android, which does not build upon WebOS.