While much can be said about the concept of a frenemy (defined in the oxford online dictionary as portmanteau of "friend" and "enemy" that can refer to either an enemy disguised as a friend or to a partner who is simultaneously a competitor and rival), common wisdom usually is to avoid them at all costs. However, that proves impractical in most cases, and the best bet is to keep tabs on those frenemies, just as General Sun Tzu suggests.
That brings us to one of the most powerful concepts behind Google+, circles. Circles allow users to customize and categorize their friends (acquaintances, contacts, associates, whatever) into groups. Common circles are 'family,' 'friends," 'business," 'neighbors' and so on. What's cool about circles is that you can drop and drag your friends into them very simply, they can 'live' in multiple circles and you have control over what information goes to what circle. So, here is the kicker: With Google+, it is a good idea to create a frenemies circle, one where you can dump those individuals into that circle and keep an eye on their updates, while feeding them the information you choose to.
A frenemies circle could become a powerful ally in highly charged, political business environments, giving you an easy way to keep tabs on people you would never friend on Facebook or connect to on LinkedIn. Of course, misinformation and outright deceit are very Machiavellian tactics in the work place and could easily cost someone their job, but both are commonly used in today's business environment - Google+ just makes it a little easier to automate the process.
However, there is a definite downside - what if a frenemy discovers they are on a frenemies circle, which could be interpreted as the business equivalent of President Nixon's enemies list, and potentially could wreak havoc with one's career. Also, it takes a bit of effort to track frenemies, time that may well be better spent on productive chores.
Nevertheless, frenemies circles are bound to become part of the Google+ nomenclature, and may be a sign of things to come in the world of social networking, where categorizing contacts could have political ramifications. Perhaps the best thing for Google to do would be to make sure everyone knows what circles they are classified in, preventing users from using questionable tactics in their dealings with others.