WPF has very rich support for displaying and manipulating formatted text. I’ve recently came across couple articles at MSDN on this topic. You can get an overview of the rich format support from this article. And then you can read the in-depth article on drawing formatted text.
This compares very nicely with this excellent book on .Net 2.0 Windows Form GDI+ graphics and text drawing by Eric White. Overall I am very impressed with the rich format text rendering support in WPF, despite some unresolved anti-alias issues I have on Windows XP workstations.