Yes it does. I am not aware of any plans for full menu support, including Java, as you get with PDVD or Arcsoft or your stand-alone DVD player.
However, if you right click on a bluray while playing or assign the DVD menu to a key and press that you can see a text only menu listing titles on the disc, with duration. Unfortunately there are no proper names for the titles, so unless you know the length of what you want to see you have to guess! But it is a good first start.
It is possible support for non-Java menus, as on some discs and as can be provided by AnyDVD for Java discs, might be added as it is already in beta in the open source community on XBMC.
But, full menus (and 3D support) would require a collaboration with Cyberlink or Arcsoft. Since their own media Mangement tools are so pitiful I think it could be a win-win for JRiver and who they chose, but for sure I would want JRiver to remain independent. I hate to think what Arcsoft or Cyberlink would do if they got control of Media Center!!!
it would be carnage!