When on the "Discussions" tab of a trip and you reply but tick the "Post as Private Message Tickbox" it sends a Private Message to all members that have joined the trip when I was half expecting it to send a message just to the person I was replying to (in this case the trip leader).
In this case it wasn't a major deal and honestly probably never would be, I would hope we are all pretty friendly around here but all the same it can be embarrasing when you think you are having a private conversation when in fact everyone saw what you just posted.
I think the functionality needs to either be changed so that it only sends a private message to the person you are replying to or it just needs extra clarification. ie: Post as Private Message to Joined Members.
PS. Kelvin / Site Management
I am a Web Developer by trade and would be happy to donate some of my time to this awesome site.