atrax: Yes, those are Lampropholis guichenoti. Strange aggregations like that have been reported for decades. I've seen them up to around that size (but never managed to get a picture - well done!). There are reports of them with up to around 50 animals! I've heard it speculated that they're 'mating balls', although I've never had the opportunity to sit and watch them for long enough to see what's going on. In your picture it looks like they're all biting the same place. Was that picture taken in Sydney? I've kept them for years, but I've never seen captive animals do the 'balling' thing (not that I've seen). Perhaps it's just because they're all so used to each other, always living so close together. Then again, perhaps it has happened a lot of times without me seeing it. If you put a new group together they can squabble a bit, but they very quickly sort things out and get along very well.