Confidence in being himself is the key. I have a year 3 son, and was quietly worried about what would happen at school, because of my own experience (wasn't part of the "cool" group when I was young, took me ages to find any confidence with my peers etc).
I decided when he was a baby that the only way forward was to teach him to be confident in himself, and to be proud of the things that he enjoys and is good at.
He started reception in a school where he knew no one, and a large group of boys were already friends. He kept his distance at first - I remember his first Parents' Evening, when his teacher said that this group of boys "interested" him, but he was holding back, which was fine.
I am actually so proud of him - he has gained confidence over the years, loves school work, joins every club he can, plays tennis and football, has lots of close friends, including the original group of boys, and was voted class rep this year.
It is no good trying to be cool. Gadgets etc only work if there is a common interest (we have got a Wii, and Fifa 12 is a popular topic of conversation, but so is BeastQuest, Mathletics, and the Premier League in general). What is important is that he is happy, confident, and has interests he has some element of passion about. The friendships will follow.
DS1 goes to a Holiday Club, plays football and tennis outside school, does a music class, and swimming lessons. He is still quite a shy boy, but has friends from all the clubs.
I wouldn't bother with playdates, or trying to get in with the "cool" chidlren, unless the boys are arranging them themselves (asking if so and so can play etc), but concentrate on getting him to have fun with lots of children, and making friends that way.