I assume that this question is fueled by the recent and numerous cases of "whistle-blowing" in the news (Snowden and Manning). The world seems to be questioning when, if at all, loyalty to a company, government, or country should be broken.
David E. Soles, in his 1993 article "Four Concepts of Loyalty" (published in The International Journal of Applied Philosophy), defines four different concepts of loyalty that the majority of individuals "adhere" to. These concepts are: 1) the idealist's concept; 2) the "common sense" concept; 3) the "loyalty as a norm"; and 4) the minimalist's concept.
Soles bases the idealist's concept upon Josiah Royce's concept of loyalty. For Royce, loyalty is only given when the person has a "cause" and "willingness" to be loyal. This type of loyalty is "freely given" by the individual.
For the common sense concept of loyalty, Soles relies upon Andrew Oldenquist's ideology of loyalty. Oldenquist believes that loyalty exists when an individual identifies the "object" as something which belongs to him or her (he or she has a direct interest). Oldenquist further explains this idea by breaking it down into three steps: caring for it, serving the interests of it, and having a relationship with it.
Loyalty "as a norm" concept is also defined by Oldenquist. In this concept, loyalty relies upon the ideas the community holds. Essentially, the norms of the individual's community defines what requires loyalty.
The minimalist's loyalty is defined as the concept that a loyal person "meets reasonable expectations of trust" (Lowe). In a sense, this defines loyalty through a minimum expectation from loyalty: one is simply loyal.
In answering if Soles' article helps to make sense of the concept of loyalty, I would say that it actually confuses the idea. For instance, I have my own definition of loyalty. Being loyal means being faithful, and devoted. One must identify what people, things, and ideas are valued more than the others. One intentionally values one thing over another. For example, is one's family valued more than one's employer? I value my employer; I show loyalty to my employer. That said, my family comes first. I will miss a day of work to care for a sick child.
Questions which require subjective answers are always hard given not all people see things the same way.