There has been some confusion regarding the Messaging System on PalmTalk - and what is private and what is posted publicly. I've been asked to explain the two.
There are two forms of messages - what I will call "Private Messages" which are Private, and "Activity Messages" which are public.
A Private Message is designated with an envelope icon. It is available at the top of every page (click it and use "Compose New"). It is also accessible by hovering over a User's name or Avatar and clicking the envelope icon. Or it is also available on a User's Profile Page - at the top - again, with the envelope icon. Anywhere you see this envelope icon, you can click it and send a Private Message.
An "Activity Message" is public. These are the "What's on your Mind" and "Leave a Message on [User X's] Feed" boxes where you can leave a public message directly as a Status Update (on your Profile or Main PT Page) or on a User's Profile Page - which updates his Status Update and also posts on PT's Main Status Update Page. These are "Activities" and labeled as such on the Profile Pages.
What is confusing is that both options (Private and Activity) are available on a User's Profile Page.
Just remember, that if you want to send a Private Message, use the envelope icon link - wherever you see it. That will get you to the Private Messaging Center. Any other "Status Update," like "What's on your Mind," or "Leave a Message on [so-and-so's] Feed," is public.
I would make it less confusing if I could, but I can't.