We were all excited (and surprised) with the rumours and subsequent announcement by Nokia surrounding the white Lumia 800. Being already available in black, cyan and magenta, the white variant adds a refreshed look to the 800 range of Windows Phones. Here in the UK, availability of the white Lumia 800 is exclusive to Phones4U, which has contracts available on O2, Orange, and Vodafone.
According to a blog post on the website, the handset is available for pre-order and Phones4U will be shipping the handset early March. It's unsure how long the exclusivity will last.
Source: Phones4U, thanks Richard (the other one) for the tip!