During the CTIA 2007 show, Sanyo announced the SCP-7050
as its most-protected phone, meeting 810F Military Specification, certified for dust, shock and vibration. This is relatively simple phone designed for heavy outdoor usage. The only features worth mentioning are the Bluetooth, GPS and large internal display, with QVGA 240x320 pixels resolution.
Sprint PCS offers it for $100 after rebates and you can order it now.