Mobile messaging software company Miyowa revealed that it was picked by Microsoft to develop the Windows Live Messenger app for the recently announced Windows Phone 7 (WP7) platform, rather than the software being developed by an in-house team. In a blog post, the French company says that “we’ve long been partners with Microsoft, and are their number one mobile Windows Live Messenger provider.” The app will be available via the Windows Phone Marketplace when WP7 is released to the public later this month – it is not clear why Microsoft is not shipping devices with a Windows Live client pre-embedded.

In addition to Windows Live Messenger support, Miyowa’s InTouch5 product can aggregate Facebook, Twitter, Yahoo! Messenger, Myspace, Gtalk and AIM into a single app. It is currently unclear what features the software Miyowa has created for Microsoft will include.

In addition to its relationship with Microsoft, Miyowa has also developed messaging apps which have been embedded into apps by a range of device manufacturers and vendors – it claims 35 operator and seven handset manufacturer partners. During 2010 it announced the first Nokia device to include an embedded Miyowa client, the Nokia C5 for Bouygues Telecom, with its technology also having been used in devices from Huawei, INQ Mobile, Sony Ericsson, and ZTE. It also provides software for the Samsung Craft, the first commercially available LTE handset, sold by US operator MetroPCS.