Jon Rubenstein was an Apple VP and the head of iPod until 2006. In 2007 he went to Palm and spearheaded their smartphone development. You don't think he had a "high-level idea" about the iPhone before he left? I don't see him in court, and given Apple's (and Jobs') penchant for intellectual property litigation that says a lot.
Given Palm being another company with deep pockets, it may not say all that much. Elite companies don't like having legal battles because most of them are Pyrrhic victories and should only be fought over major matters.
True, but Palm would have been more difficult. You cannot get a patent for "build a better phone" or "interface that doesn't suck" which is what they likely would have gone after Palm for. Also, there isn't a prejudice against Palm, but plenty of people view MSFT with disdain and MSFT has in some ways been victims of their own success making them an easier target.