Until very recently, multinationals listed in the US but not resident in the US were required to show a reconciliaton of their local GAAP financial statements to the US GAAP equivalent. Many of these large companies (based in Europe and the Far East) incurred high costs in time, energy and hard cash in preparing US GAAP accounts for this purpose only.
As a result, listing on a US exchange started to appear less attractive to these and other new potential listings. The SEC had been mulling over how to deal with this for a while, and fairly suddenly has now announced that these companies do not need to provide the reconciliaton to US GAAP. As a result, many large companies have already opted not to produce the US GAAP figures.
The next major step would be if the SEC decides that US companies who decide to report under IFRS do not need to provide US GAAP figures. As IFRS gains traction around the rest of the world, nobody wants to be left behind as the special case. This is still a way off, and their is also plenty of trouble brewing with IFRS (Phase 2 Insurance Project particularly) but it does look like many US accountants will need to polish their European language skills.