There're many iPhone client for micro-blogging services, which connect each other by answering the question: "What are you doing?"
However, what you can do by this application is only posting.
Peach can't display updates by others, upload a photo, nor update your location, but specializes in "posting."
Peach supports posting to several micro-blogging services such as Twitter, Timelog and Wassr, so you can use this as a cross-posting tool.
"You can post it whenever you want"-- that's what Peach is.