Looks like some upstart company called LoudTalks has launched a Windows Mobile version of their desktop push-to-talk software.
So what's Loudtalks anways? Think IM client with instant voice chat on the PC--it just sits there and you can simply hit F7 to chat with your friends.
Now they've adapated that for WM so you can have instant convo's with your peeps. The download is just shy of 3mb, making it quite large for an IM app. Plus, at this stage of developement you have to (1) create an account and (2) have a working desktop version first, otherwise you can't add people.
Of course Palringo has offered something very similar for a long time and we're still unsure here of registering for yet another IM/PTT service, but some of you may want to try it out.