Commentary: Working with Starbucks is hardly without risk By MarketWatch March 10, 2011 SAN FRANCISCO (MarketWatch) — A word of advice to Green Mountain Coffee Roasters Inc.: Be careful who you invite over for a cup of coffee. After a tense standoff in the fast-growing world of single-cup brewing, Green Mountain (GMCR 60.58, +16.94, +38.82%) and Starbucks Corp. (SBUX 37.85, +3.31, +9.58%) have joined forces. According to their joint statement, Starbucks will add its powerful brand name to the lineup of coffees and teas available in K-Cups for use in Green Mountain’s Keurig brewing machines. In exchange, Vermont-based Green Mountain gets to place its Keurig single-cup brewers in Starbucks stores, gaining instant access to millions of coffee lovers via thousands of outlets across the planet. This marketing bonanza sent Green Mountain shares soaring as much as 40% Thursday. And to think, less than a month ago Starbucks was making ominous comments about how it intended to crush...