According to our source, Apple will be set to unveil Xeon-based Xserves. It is unknown what speed they will come in, or whether they will pack dual processors, but speculation would indicate that Apple forgo Intel's top-of-the-line 3.0 Ghz Xeon in order to meet the heat constraints of the 1U Xserve.
Mac Pro and Displays
According to our source, both Core 2 Duo (Conroe) and Xeon chips will be used. Along with the new desktops, Apple will also unveil new displays with up to 1:1000 contrast ratios, built-in iSights, and built-in IR receivers for use with Apple's remote.
Also mentioned was a slight design update and Merom (Core 2 Duo Mobile) upgrade for one of Apple's products. Currently, MacRumors believes this to be in reference to the MacBook Pro, however with iMac supplies dwindling at many retail locations, the possibility exists that it could also be the target of an upgrade.
A half-dozen or so features of Leopard are said to be ready to be displayed during Job's keynote. While not mentioned specifically as the features to be displayed, the UI is said to be updated, as well as better functionality for businesses, Safari improvements, and the underpinnings of "OS 11". The most intriguing hints are that Apple will incorporate 3d effects in an impressive new feature of Leopard.