As capicola pointed out, Flash is already available for Android phones, though you need to have Android 2.2 or higher. Most newer phones have been updated to this version, but if you're unsure of what you have you can check it in your Settings under About Phone.

As for on your iTouch... never. Apple has been very anti-flash. Apple users seem to think that having the option of viewing Flash means they're somehow forced to spend all day running flash and their phone is going to melt down. Flash on my Android phone has been responsive and I've never once had a problem with it. You can make it so Flash objects are "on demand", that is off by default and you choose what you want to load, so you don't have a bunch of ads or Flash files you don't want starting unexpectedly. It's great for being able to view websites that still use Flash or videos that don't have mobile options.