Is it 18 giga-lightyears away now, or was it 18 giga-lightyears away when it exploded?
This was discussed in the press conference today.
The greater the "repulsive" effect (dark energy?), the older the Universe is, relative to the age that would be acertained by the Hubble parameter alone.
The example given in the press conference was that based only on Hubble expansion observations (no repulsion/accelerating expansion effect), the age of the Universe would be about 9 billion years. When they factored in the repulsive effects on expansion, the result was about 14 billion years, which coincidentaly, is almost exactly the figure that these scientists came up with using the completely independent white dwarf cooling model methodology.