The law pretty clear here:
Celebrities particiapate in public life. However this does not mean they live 24/7 in public. When a celebrity makes a public appearence it is not private and not part of the privacy. The right of privacy itself is still active. For example many celebrities decide to hide their children from public (eg Michael Jackson) or to not talk about their private life in general.
However the right of privacy can be weakend by the celebrity. Some easy not Hogan related examples:
Angelina Jolie has publically talked about her breast amputation to make people aware of breast cancer. Her families history regarding breast cancer and her amputation are clearly part of her privacy. With her public announcement she "lost" the right of privacy regarding this topic. This means the media is legitimated to discuss this topic over and over again. Also they may discuss if it was the right step to make this issue public. However although they know that AJ got breast amputation they are not allowed to fly with a helicopter over here house and check if she is lying topless by the pool and how she looks topless now. This part of her remains private (unless she decides to make topless pics available to the public).
Another example to weaken the right of privacy would be the Ossbournes. They have decided to let a camerateam film their (staged?) family life, which is again usually part of the privacy. With their public appearence people are now legitimated to discuss the TV show and even related stories (such as the happenings with Ozzys son and daughter outside of the show).
Another example would be Britney Spears who lived a very public life a few years back with all her horror stories. Just remember the skirt accident. Her right for privacy was definitly weakened around that time. However today she has decided to live a more silent more private life. Her right for privacy is stronger today. You are not allowed to put a camera under her skirt and check if she got some panties meanwhile.
Summed up a celebrity does have the same rights of privacy as every other human, but the more public they make their private life, the less they can insist on their right for privacy. Its really up the the celebritys behaviour and can even increase/decrease over time (as it happened with Britney).
Hope this helps. Please dont be rude with me if something is unclear. I have just realized that I have a few vocabularies missing.