As of now, PDAshop.nl has the new silver HTC Desire showing as being available on the 9th of April. Not too long for some to wait I hope.
Meanwhile, Phandroid reports that "Dutch carrier BelCompany are reporting the Silver color option as an exclusive" and after read this page from BoyGeniusReport, I think we may see this option very soon in the States. If you are in the market for a silver HTC Desire right now, check with your provider. Who knows, they may have a similar special deal. Good Hunting!
Images from Robert Webbe's Flickr account