Avocent, probably best known for their KVMs announced two products that allows managing a Windows Server remotely from a Blackberry or Windows Mobile based device.
Avocent Corporation Unveils New Products to Enable Management of Servers from Smartphones

Using SonicAdmin QR software, system administrators can access any server allowed by their Active Directory profile to view server statistics, shutdown and reboot servers, view event logs, view and manage processes, manage Active Directory user accounts, and run Quick Commands such as ping, ipconfig and traceroute.

SonicAdmin Pro software offers additional functionality, adding Windows services management, file explorer, file search, file and folder properties, file editor and a Command line interface. The Exchange Server management extensions include viewing queue properties as well as freeze and unfreeze queues and force connection commands. Active Directory management adds user group management and mailbox properties