The probably longest patent dispute in IT history started back in 1999 when Eolas Inc., a spin-off of the University of California, sued Microsoft for an alleged patent infringement in Internet Explorer. Eolas claims that it invented the idea of embedding external program objects into hypermedia documents or in other words the plug-in technology, which is used in all Web browsers today.
After 8 years of legal action Microsoft lost the dispute, although the meaningfullness of such software patents is highly disputed and the plug-in idea is older than the Web, anyway.
In April 2006 Microsoft attempted to circumvent Eolas' patent by introducing an unnecessary extra click for external objects, the infamous "Click to activate" prompt.
The good news is that Microsoft announced yesterday that it settled the dispute and will remove the ActiveX activation in an upcoming update, scheduled for April 2008. The bad news is that Microsoft is licensing the patent from Eolas under unkown conditions. Opera has already included a similar activation procedure and as Eolas states on their Web site there will be no exception for commercial open-source Web browsers such as Firefox. I am now curious how Mozilla will react on it.