Just to weigh in... I have had users complain about the logo. They think that it means that the notes are not really from my company somehow.
I agree in giving credit where it is due, especially with free software.
That being said, I'd gladly
pay for a version of phplist with all logos/credits removed.
That way, casual users can use the free version and help spread the word on this great program and business users can pay (a nice $ way to support the program) for the ability to automatically have all credits removed.
Seems like the folks at phplist and the customers would win both ways.