In the past few weeks, I've heard two different intelligent people say the phrase "mute point" instead of "moot point".  At first, it annoyed me that anyone would fail to meet the unattainably high grammar goals I secretly set for myself and others.  But then a link pointed out that these people might think the phrase refers to mute as in "if something doesn't matter, it's not saying anything. It's 'mute.'"  I have to say I hadn't considered that, and it kind of makes sense.