Silverlight 1.0 didn't have much in the way of accessibility - essentially the equivalent of alt tags. Silverlight 2 will change that by exposing a full accessibility tree to accessibility tools in builds post Beta 1.
In this video Mark Rideout from the Silverlight team discusses how Silverlight 2 handles accessibility. Mark was PM for accessibility in Windows Forms, and is also PM for accessibility, textbox and input in Silverlight 2.
If you have never witnessed someone using a screen reader to navigate a web page, be sure to check out this video (especially the last couple minutes where he speeds up the rate to what he normally uses)
What will Silverlight 2 provide for accessibility?
- Tabbing and tab order
- Focus and Keyboard Input
- Exposed Accessibility Tree (through UIA - UI Automation) for screen readers and other accessibility tools
- Accessibility Information directly in XAML Markup via AutomationProperties attached properties such as name and help text
- Support for AutomationPeer as in WPF
- Other capabilities such as notifications for high-contrast requirements
If you want to see the accessibility tree for your applications, download UI Spy.