Have you (or any of your colleagues) studied Rijndael-256? I'd be interested in seeing your analyses and conclusions if you have.
I wouldn't go out of my way to use it, but I flinched a little when this report suggested its use was a vulnerability. I don't think 32 byte blocks are much better than 16 byte blocks, but 16 byte blocks are much, much better than 8 byte blocks, and so I feel like I should be consistent.
That does not appear to be the case this time, however, since the page acknowledges (in an update) "256 bit block" and the fact that it isn't AES. So I should probably make note of that in the CryptoFails post.
I'm unsure how well the analysis of AES (and the attacks against it) carry over to Rijndael-256, so I'd be hesitant to actually recommend it without asking a cryptographer... but, like you, I'd be very surprised if it was a source of vulnerability itself.
There are probably zero crypto implementations that that contain the string "AES" that use Rijndael-X/256 that aren't broken in some other comical way.
Are all the studies on the 128-bit block variant of Rijndael (the one christened as AES) also applicable to the 256-bit block variant? I don't know the answer to this question.