Help on some questions, please!

[lorddrake]

I was thinking and, since I'm away from my books right now I got a little confused on some things.

First - Does mindblank blocks mindsight and (greater) arcane sight? For example: dude 1 greater arcane sees dude 2 with magical items and spells on him.

a) Does dude 1 see his magic items auras and effects...
b) Does dude 1 see nothing...
c) Or none of the above?

Second - If mindsight is no good against those, what is?

[The Random NPC]

Mind Blank seems to protect one from Arcane Sight, so Dude 1 would see nothing. For Mindsight, you would have to decide if it was a device that detects thoughts, or if it was a divination effect. You could also decide it runs on telepathy, which, in turn would have to be determined as a divination effect.
If any of those are the case, Mind Blank would protect you from it.

[Yora]

I think it is stronly implied that "information gathering by divination spells or effects" is meant to apply only to the creatures mind. The next sentence "Mind blank even foils limited wish, miracle, and wish spells when they are used in such a way as to affect the subject’s mind or to gain information about it." mentions the mind directly.

With arcane sight, you would not be able to determine if the creature affected by mind blank has any magical powers. But it still would work detecting if any of the items it carries are magical, and if it's under the effect of any spell that is not mind-affecting.

[The Random NPC]

Strongly implied and a reasonable house rule. But I believe RAW would hide the information of any attended magic item. Honestly, I would rule the same as you, and have it foil Mindsight, in a real game.

[lorddrake]

Thanks, this helps a lot.