Guys, ad hominem attacks make you both look bad. Let's avoid that and try to concentrate on the issues.
That said, this point has been argued to death. Nevertheless, there are generally two truths which make themselves evident after a lot of hashing:
1) We simply do not have the research to state that MDMA is neurotoxic in humans. There are so many confounding factors in the studies that have been done that they're almost totally inapplicable. For instance, the inter-species dosage scaling model almost unanimously employed in biological assays of MDMA's neurotoxicty suffers greatly from the fact that small mammals such as rats produce toxic metabolites at an enhanced rate due to their fast metabolism. The inter-species scaling model contradicts this fact, recommending extreme dosages where they should actually be administering smaller ones to compensate for the increased production of toxic metabolites. Behavioral studies in humans have been admittedly population-biased, to the extent of recruiting their subjects from raves and other such events where a host of factors would dictate one's disposition simply by their attendance. In summary, the research just isn't there. I agree with fat_bunnies that this is because of MDMA's illegality -- there's an incentive to prove MDMA's neurotoxicity, but none to prove how to use it safely (or whether this is even possible). Studies are designed to provoke a neurotoxic reaction, and anyone who's done research knows that there's a definite impetus toward providing the results that one expects.
EDIT: Actually, after writing this, I realized that the biological harm picture isn't so clear. It's obvious that releasing massive amounts of neurotransmitters is going to lead to depletion, downregulation, etc. Also, using an amphetamine analogue carries all the risks of normal amphetamines with it, even if the risks aren't as pronounced with MDMA (since it's not as effective in its stimulation as, say, dex-amphetamine). The best advice I guess we can go on is to practice caution and keep in mind that there's a risk/benefit ratio in which the risks are not entirely known, which makes the whole thing more risky but still potentially worthwhile.
2) Anecdotal reports indicate that using Ecstasy (note that I'm not going to say MDMA here) causes some harm. Lacking longitudinal studies, it's hard to say whether this harm is permanent. It's also difficult to say whether this harm is a result of the drug itself, or a result of living weekend to weekend and having one's life revolve around an altered state. I imagine that simply considering oneself to be a drug user introduces a number of psychological issues, apart from the effects of the drug itself. As such, I don't think we can say much for E's physiological effects, but I think it's prudent to caution people not to construct their lives around the drug, or use too often or at high dosages.
For the record, I see nothing wrong with fat_bunnie's grammar. On the topic of FDA-approved neurotoxic drugs, Ketamine is employed as a painkiller for children and the elderly, but potentially causes neurotoxicity (Olney's lesions, to be exact). Doctors circumvent this by using an NMDA inhibitor, which blocks the neurotoxicity. There may be a similarly simple solution for MDMA, but the current trend in MDMA research isn't helping us reach it.
