[quote="Godfollower, post:10, topic:235359"]
The other posters have already made some good points, but I wanted to point out a small but significant sublety: I believe that the correct translation is "I am who am" and not "I am who I am" -- that is (as steveb1 and Joe Kelley pointed out), He didn't say "I'm this" or "I'm that;" He pointed out that He is existence.
Actually, the Hebrew has 'ehyeh asher 'ehyeh, a phrase rather difficult to translate (literally it would be "I-be that/which/who I-be"). The question rests on how we are to understand the imperfective (the imperfective in Hebrew was used for incomplete or ongoing actions, and thus could imply either the present or future) 'ehyeh.
Translating 'ehyeh as "I-be", "I-am" or "I-am-being" does present us with considerable exegetical difficulty, but so too does translating it as "I-will-be".
The crucial difference between the two is that whereas the words 'I-am' in isolation can be meaningfully understood in the context of God’s self-designation, the absolute declaration 'I-will-be' cannot, if read as a reference to the Divine nature. The 'ongoing, continuous being' idea of the verb would certainly indicate that God is not bound by time: He just 'is'. The traditional English "I am that I am" and the Septuagint (and Vulgate) paraphrase ἐγώ εἰμι ὁ ὤν / ego sum qui sum "I am who is/am" understands the Name as referring to God's unchanging, ever-constant, ever-present nature.
One problem with rendering with in the future tense is that if God were to designate Himself in terms that specifically refer to the future it could be misread as implying that God is not yet God (taking 'ehyeh to refer to His nature), or that He is in a state of becoming somehow different to how He now is, both of which are rather absurd and unacceptable to the Mosaic monotheist, and even defy coherent articulation.
Thus, when referring to God, future 'ehyeh would require some expansion in order to render it theologically meaningful, one such as the oft-suggested "I will be with you" (cf. Exodus 3:12), which turns it into a reference in relation to His actions within temporal space (this is the interpretation Aquila and Theodotion favored). In this interpretation, the Name does not (merely) reveal the essence of God but His relationship with His people. They need to know not merely that He 'is' but that He will work on their behalf: "I will be understood by my acts and revelation."
The rabbis of the Talmud have paraphrased the passage: "The Holy One, blessed be He, said to Moses: 'Go and say to Israel: **I was with you in this servitude, and I shall be with you in the servitude of the [other] kingdoms.' He [Moses] said to Him: 'Lord of the universe, sufficient is the evil in the time thereof!' Thereupon the Holy One, blessed be He, said to him: 'Go and tell them: I AM has sent me unto you.'" 'Ehyeh-asher-'ehyeh is thus interpreted as a statement of God’s abiding presence with Israel, while the 'ehyeh of 3:14b is interpreted as a shortened version of this declaration and as a gesture of God’s compassion towards Israel in response to Moses’ appeal on their behalf.
Such profound depth for three simple words. ;)