First, I'm already aware of Izzy's great answer on Remote control apps.
On one hand, if you have an iDevice (Apple iPhne, iPod or iPad) and buy a headset with a "made for iPhone" logo, you can pretty much be sure that all the functions and buttons on the remote control will work properly, namely, skip track back and forth, fast forward and rewind, play, pause, etc.
The question is if there is such a standard for Android? Heck, it's open source so you perhaps just have to look at the source code.
If there is a standard is it a standard on the device's side (phone, tablet), or on the headset's side?
If there are 'variants' what are they? If we are talking about current 2012-13 devices. (Eg. the Samsung variant does this, the stock Google variant does that.)
Is it easy to navigate yourself through the headset jungle if you are a music and podcast lover?