Finally, a Lync client for the iPhone is in the works, don't get too excited though, Microsoft says it will be released 'in the coming year' - looks like we will still have to wait a while.
http://lync.microsoft.com/en-us/Product/UserInterfaces/Pages/lync-2010-mobile.aspx
Until then, use iDialog fom Modality Systems which is available through the iStore, more detail here: http://www.modalitysystems.com/idialog/
