Here it comes! Microsoft and three online retailers are open today for pre-orders of the Zune HD in both 16 GB (black, $220) and 32 GB (platinum, $290) variants. Here are the links (some aren't available yet for some reason)...

Zune HD 16 GB
Amazon
Best Buy (not yet)
Wal-Mart (not yet)
Microsoft Store

Zune HD 32 GB
Amazon
Best Buy (not yet)
Wal-Mart (not yet)
Microsoft Store

Related: Zune HD to Ship September 15, Available Now for Pre-Order (Me, WinInfo)