Do you happen to have a link to the cupcakes you are talking about?
There are several techinques that end in the word transfers, so it is hard to say with out seeing them.
http://www.flickr.com/photos/lecupcake/220808611/
Here you are.
Aww okay. Those are chocolate transfers. Chocolate transfer sheets are colored cocoa butter (someone correct me if I am wrong). You spread your warm chocolate on them (or lay them on the warm chocolate) and the warth from it melts the cocoa butter. When it cools or is hard you will remove the backing to the transfer sheet and it will leave the pattern behind.
You can find these online in several cake shops. Google "chocolate transfer sheets."
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