I second what Peachy has said. My son was a terrible hitter/pusher/biter at the age of 3 yrs. At 4 yrs, he is better, but still prone to being very pushy and having outbursts of aggression. At his old nursery, the staff were fairly lame in their approach, despite lots of meetings and me and DH being totally on board. They ended up virtually excluding DS - he spent more time sitting on 'the naughty corner' than anything else - which (surprise surprise, didn't work). There were some horrid parents there, too - throwing dirty looks and talking about us behind our backs. How is that helpful, constructive or setting a good example to the children? In the end we removed our DS.
His 'new' nursery (been there since Sept 08) are fabulous in the way that they are dealing with it. We have got the inclusion manager and learning mentor on board and have got a referral to a community paediatrician. Nobody actually thinks he does have any diagnosable problem, but we are going down all the correct channels to rule it out and/or get a statement and get DS the help he needs.
And do you know what has been the most wonderful thing? the parents at the new nursery have been overwhelmingly supportive. DS still gets invited to all the birthday parties and playdates, despite the fact that he can be 'difficult'. I am able to discuss the issue openly with other parents and it makes a world of difference to everyone involved. The other children know that DS needs a bit of extra help with his behaviour, the parents are sympathetic and DS is improving no end - I believe as a direct result of the great attitude of everyone at the nursery.
If someone launched a petition against my son and I had other parents whispering in the playground...God, I can't imagine how detrimental that would be for my son and for the whole atmoshere at the nursery, which would affect all the children.