It depends exactly what you mean by "target".
Essentially, the cupcake emulator and SDK tools are being modified right now (work still not finished) to support several platforms and add-ons.
A "platform" corresponds to a given version of the Android APIs, and provides a full set of images for the emulated kernel, system images, android.jar and default skins
An "add-on" is optional and references a platform but provides additionnal things, like a new system.img that may contain additionnal framework APIs, the corresponding android.jar or other jars, some skins.
This is done so that third-party can provide their own add-on without having to releasing a full SDK themselves
(i.e. using thes same DDMS / Eclipse plug-in / emulator / mksdcard / etc... binaries).
The only exception to this would be if you need to change the emulated hardware, which would require its own emulator binary.
We will let you know when everything is completed. Right now, using the cupcake SDK is not recommended since things are still highly volatile.