It might work but this is a poor solution. Resistor based level shifters fail with many newer SD cards since new cards have edge detectors for the signals and resistors round signal edges.
This is the reason that almost all commercial products now use semiconductor buffers/level shifters.
Good luck if you try it. You might want to download the new SdFat beta and enable CRC to detect any data errors and slow down the SPI clock.
The SdFat beta with CRC is SdFatBeta20120327.zip Google Code Archive - Long-term storage for Google Code Project Hosting.