JetBlue tried marketing on Twitter but eventually realized that it is a conversation medium. In recent months JetBlue have added a "Currently on Duty: " tag to the bio so that people realize there is a person behind the company tag.
Corporations don't know what to do with Social Media. Social Media in corporations is all over the place. It is in the technical teams, or in PR, or in marketing.
@JetBlue was developed as if it was a person. It should be consistent with the core values of the brand. This transcends the style of a specific person.
"Twitter is people powered RSS feeds."