Silverlight 4 is more powerful than the version 3, and we can easily implement rich contents by use of it.
One of them, there's RichTextArea ( mostly similar to RichTextBox in WPF ).
and New MouseButtonHandlers (MouseRightButtonDown and MouseRightButtonUp) is going to be supported (Silverlight 4 or later).
So a ContextMenu can be implemented.
2. Font Size
3. Color Selector
4. Insert Hyperlink
after releasing Silverlight 4, we can upload richtext for comments on Blog or somewhere like forum sites by silverlight application.
by use of sort of following format.