(UPDATED with corrected information!)
Manga UK just twittered that they'll be releasing Mamoru Hosoda's "Summer Wars" in the United Kingdom next September, and our good friends from Affenheimtheater are confident that this will indeed include a BluRay release.
(According to Manga UK you lucky people in the United Kingdom will actually be getting a theatrical release in September, with DVD and BluRay following later that year. See the comments...)
Manga UK may not be my most-trusted distributor (cough-understatement-cough) but on occasion they do get everything right, so let's keep our fingers crossed for this one!