So if you want to have the plasmoid for your KDE4.2 desktop, it should be straightforward to compile/install.
On the screenshot you can see the plasmoid in action. There are two instances, one on the panel and one on the desktop. The one on the left is the KDE3 one.
It's worth to mention that the plasmoid already supports more featues than the KDE3 version. Features include:
- show all cpus (for computers with multicores)
- tooltip updates continuously
- nicer visualization (maybe needs some more tweaks)