An alert Lync forum member, TIM_MCP, noted that Lync Mobile appears to be listed on the WindowsPhone Marketplace, but not yet available. TIM_MCP noted that when he clicked on a Lync meeting URL it will take you to the Lync Mobile page on the Windows Phone Marketplace.
Since Microsoft has communicated that the Lync Mobile client will arrive by end of year 2011, this is no surprise. It should be noted that Microsoft Lync Server CU4 and mobility components will need to be installed on the backend before you can use the Lync Mobile client once it is available for download.
Below are the screenshots of the Lync Mobile app shown on marketplace: