I received my Region B version of
Let The Right One In today. It had been widely reported that Optimum's version has the proper subtitles.
When I found at least one source saying that the Blu-ray is region free, despite the B-logo on the back, I went ahead and took the risk.
I am happy to be able to report that the disc is indeed region free
It played without problems (o.k., I haven't watched the fillm yet, but menus displayed and I skipped through some chapters) on my Region A PS3.