Wal-Mart is testing a smaller-than-average Supercenter in Tampa, Fla., that could solve its market penetration problems in California, where stores larger than 100,000 square feet are prohibited, and New York, where space is at a premium. The 99,000-square-foot store is a 70/30 blend of a traditional Wal-Mart Supercenter and the retailer's Neighborhood Market concept.