I submitted the change to the Arduino crew, and another user pointed out some changes required to other files. I attached Ethernet.h and Ethernet.cpp to this with the changes required to use the w5200. These are from the IDE v1.0.1-rc1 ethernet library.
edit: Here is the report. If you have anything else to add, now would be the time. http://code.google.com/p/arduino/issues/detail?id=898
This code works with both the w5100 and w5200. To use the w5200, you must open w5100.h, and uncomment the "#define W5200" statement.
// change this
// #define W5200
// to this