Just putting this post up to warn users of HIMS products, and Braille iOS users in general that iOS 5.1 has broken support for some Braille Displays. I discovered this the hard way after upgrading both my iPad 2 and iPhone 4. In the case of my BrailleSense Plus notetaker, all input is disabled. HIMS tech support has told me that Apple has said that it is a problem on their end, and it has been identified. However, they also simply said that it will be fixed in a future firmware update. This has not been confirmed by anyone on the Access Tech team, but there are reports of this being a problem for some Baum displays as well. If you have not yet done so, it would be in your best interests to check with the manufacturer of your Braille display to ensure it is not affected by the upgrade bug before you upgrade.
I hope that this helps to save some of our readers from this headache.