Defense and federal services businesses worth billions of dollars are considered up for potential sale but -- so far -- potential buyers are playing coy. Lockheed Martin, BAE Systems and L-3 Communications have all announced in recent months that they are reviewing some of their services work for divestiture. At the same time, SRA International has filed to go public and Computer Sciences Corp. has begun the process of separating its U.S. public-sector work from its commercial and international work,...