The Lotus v. Borland decision was, in fact, about an interface that was keystroke-for-keystroke identical between the two applications. Again, there's a very clear case here for copyright infringement of the code. Mixing that with a much less clear case based on the status of the "interface" is just not a good idea.
Lotus v. Borland was not the same. As a matter of fact it was a very stupid lawsuit and rightfully dismissed.
>None of the source code or machine code that generated the menus was copied, but the names of the commands and the organization of those commands into a hierarchy were virtually identical.
In this case MS not only copied the interface of plurk, but from the look of it they also stole the code. Such a blatant copyright infringement has never happened before at this level to the best of my knowledge.
Your claim that it is "legal to copy UI in US law", based on the above example, is false.
Copying a menu, its command name and hierarchy is not the same as copying an interface. A menu is only small sub-set of user interface.
