Palringo, the cross platform IM app, is now available as a public beta in Marketplace for free:
We would like to invite you to try out our new public Beta for Palringo on Windows Phone 7. You can utilize all of Palringo’s core functionality including sending text, voice and photo messages to groups and friends.
Palringo is the leading cross-platform messaging app available on all major mobile devices as well as PC and Mac.
The Palringo Windows Phone 7 Beta allows you to stay connected and socialise with friends on iPhone, Android, BlackBerry, Windows Mobile, Java, Symbian, PC, and Mac, or build new relationships within our community of over 320,000 groups. These groups cover every area of interest from sport and entertainment to gaming and technology. You can even chat with your friends on other social platforms such as Facebook, Windows Live Messenger or Yahoo! Messenger.
Palringo Windows Phone 7 Beta is available in English for free.
I have a feeling this is going to get a lot of downloads very quickly. You can get it here.