I've heard of it, but it doesn't mean I like it. Keeping 4 adult geks of different species together with no problems doesn't mean that it was good for them, either. I keep my female Leo in a 20-gal tank, and I feel thats a minimum for her, let alone 3 more geckos. I will probably be getting her more spacious accomodations when I find some extra $$. Also, I believe the habitat of Leo's and Fattails are similar, but not necessarily so for Alligator (I'm not familiar with this species, do you have a scientific name?) or the other gecko.
I don't have all that much experience myself, and I don't mean to rant, but hearing of these situations annoys me. Well, thats my two cents, we'll see what others with more experience think.
Take care,
Nick
0.1 Leopard
0.0.2 Crested
1.2 Flying coming next week 