On the usages of I'm there

An English place adverb there basically does not refer to a place which belongs to the speaker's territory at the time of utterance. However, there is an expression, I'm there, which appears to violate this condition. I examine the usages of this expression as well as related expressions, which include a case where there indirectly identifies a place where the speaker is at the time of utterance, a case where it metaphorically refers to a "state", and an idiomatic usage meaning, "I will definitely go there.".