According to Hobby Japan magazine May issue, an OVA of Queen's Blade
was revealed. The title is "Queen's Blade: Utsukushiki Tōshi Tachi". The official announcement will be made at Tokyo International Anime Fair 2010 to be held on March 27th.
Source: Scan of Hobby Japan
Updated on March 25th
Media Factory announced at TAF 2010 that the OVA is a six-volume series and the first volume will be released in August. It's a sequel to the TV series.
Source: Poster at TAF2010