It does have something to do with the mind, if interpreted in the correct manner. His Geass is the ability to read movements based on subtle hints from the thoughts of others. He's shortened it to simply be "prediction".
It's not lame. Take a look at one of the earlier episodes where FLEIA is introduced. Its ability is not destruction. It's something probably more devastating to those caught in the blast, but easy enough to both counter and figure out.
I have to admit to being a little surprised at Lelouch's actions. I'm still not exactly sure what he wants. Does he want to rule the world? Dictatorship? What's the manner of his thought process, and how is he going to make his desires work?
Nunally already has the ability to tell truth from lies. Remember when she was talking to the adviser? Or Suzaku? She doesn't need Geass for that. Since she's blind, she can better use her other senses. She doesn't need to feel people, she can hear lies from the tone of voice, heartrate, feel vibrations, etc.
And, about the Lancelot. Remember what they said about it. They're all using 8th Gen Knightmare frames. Lancelot Albion is a 9th Gen frame. It's not Lancelot. Remember that Suzaku asked specifically for the Albion at one point? Earl stated that he'd rather Suzaku used the regular Lancelot.
What I'm more interested in seeing is "Schneizel's Mask". I think he also has a Geass ability based on that title, but I could be wrong...
