He's not popular .. He's a bully!

So ...
Forget my post on popularity.
It seems that Matthew is not ruling the daycare with his friendly antics, but rather with an iron fist.
That's right. He's a bully.
Yesterday when I came to pick up my sweet adorable angel from daycare I was told that he has been having some issues with aggressive behaviour. In other words, he is bullying.
I was actually pretty upset about this.
Matty is a really sweet loving kid, but he is also big for his age and he would be quite a good bully. He's also really strong and so if he pushes another child he could really hurt them.
So ...
What do I do?
I asked the teacher who has been working with toddlers for years. She told me that this is pretty common with toddler boys, especially at this age when they are still really learning to communicate. It's easier to push someone or bite someone to get a toy than to ask them. So, she said that it's something they will work through, and are asking us to work on at home.
Of course I will.
The interesting thing about this is who he is picking on. At home, he attacks Mike way more than he attacks me. He often bites Mike and hits Mike and pushes Mike. He's aggressive with me but not nearly as much. It's like the Pomeranians who take on the Pit Bulls. What's with that?
He's like this at daycare also - he is way rougher with the boys than the girls (unless the girl is aggressive too).
There are a million books on the issue. My favourites include "teeth are not for biting" and "feet are not for kicking".
It's just so frustrating. Mike read online that toddler boys are more aggressive than wild animals. This seems pretty accurate judging by the bruises we are both covered in.
But, then he is also really sweet. It's like he has mood swings. One second loving the next second attacking.
I'll have to do more research. My goal is to raise my son so that he can stand up for himself when necessary but also treats people with kindness and respect. Is this too much to ask for? I hope not.