Defining the practice of law

Part of our discussion yesterday had to do with the question of what exactly is the practice of law. This has never been an easy question. The ABA tried and failed to put forth a model definition of the practice of law. The Model Rules prohibit unlicensed practice, but do not attempt to define the term "practice." One has to turn to the official comment to get the guidance that "The definition of the practice of law is established by law and varies from one jurisdiction to another." (Official comment to Rule 5.5)
If you look at the following definitions from various states, some by statue (maybe even some by rule - I haven't read all 51), you'll see they do vary quite a bit.
It isn't necessarily something one can know by "smell test" or "gut feelings." I can think of one time when I complained to a practicing Vermont lawyer about how people tend to ask law students (or recent graduate friends) annoying legal advice questions. I never want to answer those questions. I see possible liability - especially since I am still not admitted to the Vermont bar (although I will be March 31, 2010). However, the lawyer said I should be fine answering casual legal questions for friends because I was not doing it for money. Look at Vermont's definition based on In Re Welch in the link above. I sure think one could violate that one without charging any fees. In Alabama (just to pick a random example from the top of the list), it seems like you might be okay if you don't appear in court or charge a fee. (Anyone want to be the one to test that?)