Accessibility option in Android 2.1 I own Xperia Mini Pro which has Android 2.1-update1.
I noticed Accessibility settings in my phones settings.
What are these settings and why these settings are required ? 
I opened these Accessibility Settings. I can see an option "Accessibility" with a unchecked check box in disabled state. It always in disabled state. I don't know when it is going to be activated.
You need to install apps that are classified as "Accessibility Apps". The most used ones are part of the Eyes-Free suite (Talkback, Kickback, Soundback, Accessibility Preferences, Eyes-Free Shell, Talking Dialer, Rock Lock, Walky Talky, Intersection Explorer), plus several useful 3rd party apps such as IDEAL Web Reader, IDEAL Magnifier, and K9 Mail.

More info - https://eyes-free.googlecode.com/svn/trunk/documentation/android_access/enabling.html