
The key to the mug is use of a 'phase change material' (PCM) which is normally used in buildings to keep them cool.
But in this case, scientists used it to fill the walls of a porcelain mug which also contained ribbons of highly conductive material, such as aluminum.
Here's the science bit: This means that if you pour a hot drink into the mug the PCM melts, retaining thermal energy, but also stops the mug absorbing more heat.
Basically, it keeps your drink warm for up to 30 minutes ... in a way too clever for me to understand.

Inventor Prof. Dr. Klaus Sedlbauer says that as different drinks are best served at different temperatures - like coffee or tea at 58 degrees Celsius - different PCMs could be used to create perfect containers for different drinks.
He even said they could create a PCM containing glass that would keep your beer at its perfect temperature of 7 degrees C ... rolleyes
Link:
Fraunhofer Institute for Building Physics