Why is "такое" always neuter in the phrase "Что такое...?" (no matter what noun follows.) Also, what does the phrase mean? "How is... like?" Thank you!
что effectively is neuter in gender.
что упало etc.
кто effectively is masculine in gender, e. g.
кто родил и жалеет, что не сделал аборт
Also, what does the phrase mean?
If simply "Что такое?" then it means "What happened?" If "Что такое X?" then it stands for "What is (the meaning, usage, appliance etc. of) X?"
So you may think the word "такое" isn't really an attribute of "X" but rather a vague counterpart of "is" (or more precisely it's like "What thing is X?"). Remember that the Russians (almost) never say "что есть X?", and saying just "что Х?" is very ambiguous (does it mean "What do you mean by X?", or "X doesn't matter", or "What happened about X?", and so on). So the logic insists on having some additional word here, and this word must be as neutral (gender) as possible.
Considering this from grammatical point of view, "такое" is a pronoun (not an adjective!) which must be put in the neuter gender, as we're talking about some inanimate object. The logic is quite clear: the question "What is X?" assumes the answer of a kind "X is Y", and here "такое" is a pronoun used in place of that (yet) unknown "Y". But which gender is "Y"? You may expect the animate nouns to keep gender the same in any "X is Y" sentence. But it's not the case with inanimate ones where the gender is a pure grammatical abstraction. So the neuter gender comes to help as usual.
UPD. Okay, animate/inanimate dichotomy is perhaps somewhat misleading here. Although in Russian we do not normally use constructs such as "What is he?", still there are cases when it's possible to put "what" along with animate nouns/notions/names etc. This could be something like "What is a human being?" type of "abstract" question, or even intentional derogatory form, and so on. Anyway, when you ask in Russian "what"-type of question, you expect the answer to be effectively genderless, and so the pronoun "такой" should be put into the neuter gender.