Few days ago Nikon Germany sent out an email to retailers stating that the Nikon D5100 is no longer available for order. The exact word used was "abkündigung" which translates to "discontinuation". The D5100 was announced on April 5th, 2011. FYI: the D3100 was announced in August 2010 and was already replaced by the D3200 in April this year, the D7000 was announced in September 2010.
The Nikon D5100 is not listed as discontinued on the official Nikon website: