This point is particularly well taken when any organization is developing it's "house style," and the cues that it wishes to use regarding tone and voice in communications.
Casual is great, when done well.
When done well.
Professional firms, especially, may tend to shy away from having such a tone, fearing the potential of sloppiness or simply an absence of "gravitas." The result can be formal and staid, and utterly non-differentiating.
When executed with care and attention to detail, however, a casual or conversational tone can be a powerful tool in forging a connection with the audience. If the whole point is to get your message across, developing and implementing strategies that make the recipient open to receiving that message is one of the ways a company can set itself apart from its competitors.
March, 2012: article content has since been put behind the paid "membership" wall. The primary point, however, is made above, even if the five details that illustrate it are now privileged information!