SAN FRANCISCO--Apple Computer on Monday introduced the Mac Pro, the company's first Intel-based professional desktop, and also gave developers a preview of Leopard, the next version of Mac OS X. CEO Steve Jobs showed off the shiny metal desktop, which will start shipping immediately, as he kicked off the Worldwide Developer Conference here. The Mac Pro offers a similar casing to the Power Mac G5 that preceded it, but replaces the older PowerPC processors with two dual-core Intel Xeon chips as well as space for two optical disc drives and up to four hard drives. The standard $2,499 configuration includes...