Support for chatting in landscape mode is the most noticeable new capability hammered into version 1.1. Turning the iPhone to the side slides up the virtual QWERTY, but it also shrinks the visible chat space to a line or two, the typical trade-off.
In addition, Yahoo has also added a dialog box for reporting bugs, which you'll find at the bottom of the Settings window. The third change is a fix for the rickety sign-in and connection issues that some users have been reporting. If you still notice problems down the road in this area, well, there's no better time to make use of that new feedback tool.