Senran Kagurascriptwriter's twitter, in addition to a drama CD, it looks like Senran Kagura will have OVA specials. At least, the first volume will have one, which definitely sounds like Katsu-neechan will give her fondling hands a work out have a hands-on with measurements :D I believe there will be more than just one special though as each volume comes out.
(sources: Tokyo Anime news, Amazon BD listing, main site)
Vivid Red Operationproduction art for Vivid Red
-Pixiv has a Windows Store app for those interested.