Skeptical mathematician Peter Woit explains here (Not Even Wrong, August 18, 2011):
The Institute for Advanced Study in Princeton announced today that Jim Simons and Charles Simonyi will donate $100 million to the Institute, in the form of matching funds for a $200 million campaign mainly aimed at increasing the endowment. For some idea of previous fund-raising by the IAS, see here.
Simons and Simonyi have donated significant sums to the IAS in the past, including $6 million from Simonyi to endow a professorship for Witten. The IAS has about 25 permanent professors, with salaries reaching above $300K/year. To get some idea of the scale of the new endowment funds, if they all went to new permanent professorships (unlikely), the number could be doubled or more. This kind of sizable increase of resources for prestigious pure research positions in math and physics, funded by huge fortunes made in the technology and financial industries, is part of a trend, with Perimeter and the Simons Center at Stony Brook two other noteworthy examples.
So, as space physicist Rob Sheldon says, fewer real world missions, but more multiverse theories.