Loaded question! You're right, all kids are different, but it would be nice to know, since we working moms don't get to see all of the playground/pre-school dynamic.
I'm a working mom too, so my son goes to a fantastic pre-school/daycare 5x per week 8-5. He's 4.5, and made a HUGE developmental leap in the last 6 months.
He can write his name. It's legible, but pretty rough. We're working on fine motor skills, got the leap frog (or Vtech?) letter writer game, and we're doing more playing with the tiny legos to build some finger dexterity.
He can count to about 50 with help here & there with the number patterns (i.e. can't remember what comes after 39.
He can read and spell some basic words like Zoo, Dog, Cat, Book, Truck, Stop, Open, his own name, the names of the kids in his class, etc. He's sounding some things out, but gets bored too quickly to sound out a whole sentence or story. I'll have him sound out key words on the pages that will be repeated in the book, so he sounds it out once or twice and then starts to recognize it by sight.
His school uses the Zoophonics program where every letter has an animal character that makes the sound. They learn the animal & sound, and then associate the letter with it. Each week there's a new letter of the week.
Also they use Handwriting Without Tears to learn to write. HWT boils down every letter into 4 main "strokes": Long line, short line, Big curve, little curve. (So a "B" is Long line down, little curve, little curve). They practice making the letters with straight & curvy sticks, practice tracing in shaving cream, with glue and glitter, etc. Then start doing markers, pencils, crayons, to trace and then write on their own. His grip isn't correct, but we're working on it.
One of the big social skills that his teachers brought up is to role play as a group. Example: If the kids are playing house, they designate who is playing dad, mom, baby, dog, sister, etc. They are just starting to do that. Up until now, most group play has been like tag, or everyone chase a ball together, not really cooperative play.
I'm curious to see what other responses you get! :-)