My son has a mentor. I bet neither of them think of their relationship as 'mentoring'. Perhaps that's because mentoring has recently been come to be viewed as Mentoring - something formal, big, a holy grail of relationships.
Mentoring happens all the time. Once we've joined a community, we're each other's best resource. The fellow guiding my son through the complexities of being a motorcycle enthusiast: discussing bikes; debating mechanics; peering at engines and nodding knowingly; getting your mom to agree to even having one in sight of the house... well, he's probably not thinking "what do I teach this kid next time?" They meet every few weeks and my son brings him the questions and theories he's been mulling. They top the whole afternoon off with iced coffees or beers.
mentoring or Mentoring - both are a wonderful tool and means to build paths. It happens at the grassroots and at the formal, business levels. Mandated, sought or inherent to a philosophy, mentoring is part of our societal fabric.