Palringo, a free multi-protocol (MSN, Yahoo IM, AIM, Google Talk, Gadu Gadu, and Jabber) IM application not unlike Pidgin on Windows or Adium on OS X, has added a Push-to-Talk solution to their iPhone client.
It’s pretty simple, as Push-to-Talk should be – select the contact, record the message, and it’s on its way. If the recipient is also on Palringo, the message can be played back (automatically or manually) right within the client. If they’re on a client that doesn’t support Palringo’s voice messaging system, they’ll be sent a link to an audio file which they can listen to within their browser.
While I can’t imagine this dethroning the bulky iDEN handset from your local contractor’s fannypack, it’s certainly an awesome bonus feature to this already useful (and free!) application.