I don't get on the forums as much as I used to. I was wondering if they changed the way you pm'd someone, I don't see the usual send a pm, but I do see start a conversation is that the same thing.
Yes, you're correct... PMs are now called "Conversations." Conversations are private (although you can include more than one recipient, if you like); so they are hidden from everyone else except for the parties involved and possibly the admins/owners. To access them, you click on the little envelope icon in the top right corner, beside your avatar.
"Profile Posts," on the other hand, are pretty much the equivalent of what we used to call "visitor messages" on the old software. Located on the recipient's profile page, they are typically visible to all forum members (unless that person has changed his privacy settings). They are also visible near the bottom of the forum's "Home" page, under the header, "Latest Profile Posts." (You can even post on your own profile to "update your status," or share what's new, as I take it to mean. )
Hope this helps to clarify things! I really like the new software, but sometimes it takes a helping hand to figure out how things work. I don't know where I'd be if it weren't for my technically savvy brothers!