Microsoft OneApp

Rumors that Microsoft is going to open an online application store, like the Apple app store, did not materialize.
In fact, it turned out that OneApp, 150Kb in size, is essentially an online application launcher. This is done in such a way as to maximize the unloading of the hardware of cell phones supporting OneApp, which requires Javascript support. Here is a complete list of supported phones:
* Nokia 3555, 5320, 6300, 6500, 6600, E50, E51, E63, E65, E66, E71, N70, N72, N73, N78, N80, N81, N82, N85, N95, N96
* Samsung U900 Soul
* Sony Ericsson C510, C902, C905, G705, K610i, K800i, K805i, T650i, W200i, W580i, W595, W660i, W980.
OneApp has both client and server components. The client is a lightweight application designed to work on the most popular phones. OneApp server components are deployed with partners, so that you can easily and quickly display popular applications.
SDK for developers promise by the end of the year.
So far, the only (read test) operator, Blue Label Telecoms in South Africa, offers the following applications to its subscribers: Windows Live Messenger, Facebook, Twitter and RSS.

A couple of links on the topic:
http://www.microsoft.com/presspass/presskits/unlimitedpotential/default.aspx
http://www.microsoft.com/oneapp/