This isn't ABC's official press release for Episode 321 Desire, so we're going to classify it as a spoiler for now. Check out this really short description of the plot for Desire, airing April 26, straight from SpoilerFix.com:

The attendings are extra attentive to a patient, who is the chairman of the hospital board; Cristina helps Burke plan the wedding.

Update [4/10/07]: Check out the official plot for Desire right here.