Apparently, Apple's new Dashboard thingummies are HTML/CSS/Javascript pages (ie WebKit) in little floaty windows, perfect for tiny Flash/SVG apps and web-updated displays.
But how do you control iTunes from one of those -- open up internal application controls to the internet? Konfabulator uses Applescript and other system commands to communicate with applications, but there's an absence of CPU or network bandwidth monitoring widgets (MenuMeters is great for that anyway) in the Dashboard screenshots, though they can read your address book and calendar.
I guess the widgets won't be able to load the actual code in from outside, unlike Macromedia Central or Laszlo widgets - so maybe there could be a separate kind of floaty widget that could load in code pages (rather than just data) from the net but wouldn't be able to access the system.