Chrome has already ported for mobile but just android 4.0, it's coming to iOS after the beta it seems but not for sure yet.
Are you trying to port or create a multi-platform application? And is it a game or just a general purpose app?
If it's a game may I recommend cocoas2D it will allow you to create games for iOS/Android and even windows phone, it also allows you to create that game for windows, mac, and linux.
If your porting an application it depends on 2 things, what language was it written with, and obviously do you have the source code.
If it was c/c++ it shouldn't be too hard to port but let's just say it was created with windows only in mind and that library/framework has no mac/linux and wp7/android/ios support you may or may not have to completely rewrite that application for your portable device.
Just my 2 cents.