MacRumors
claims to have found some screenshots from the upcoming OSX Tiger showing some new features and the ability to "disable" the UI of the parent window if a focused/modal window is on top. They also include a PDF file with installation instructions, in which OSX requires a DVD drive to get installed. Please note that the MacRumors information is unconfirmed and not official by any means.
Update: This is most probably fake, read the comments for more opinions on this.