Giving a new meaning to "portable computer," Sun Microsystems plans to sell a working data center <A HREF="http://news.zdnet.com/2100-9584_22-6126422.html?tag=nl.e589">packaged in a stackable shipping container.</A> On Tuesday, the company plans to unveil "Project Blackbox," which tucks several racks of computing gear, along with the necessary power and cooling equipment, into a standard shipping container 8 feet wide, 8 feet tall and 20 feet long.