I just left my almost 3-year-old at preschool for the first time this morning - he's a lot like your son. We said our goodbyes and I peeled him off me and left while his teacher knelt beside him with her arm around his waist to keep him from from bolting out the door. I could hear him howling all the way to the car. So we'll see.
I'd give your kiddo more time to adjust to this new situation. Say, til the end of the month. If he's reactions are still this strong after 4 solid weeks of school, then he's probably not ready. In the meantime, find out what the routine is at school and try to mimick it on the weekends as best you can (so he sees that mom and dad and his teachers all have the same rules). For example: if they are teaching him at say "May I be excused?" after meals, encourage him to do that at home, too. Have your husband practice goodbyes with him on the weekend (i.e.: before Dad leaves to go for a run, he'll give your son a BIG hug, BIG kiss, and a high five - and then out the door) And then the same at the school all week - no lingering after the high five. I'd also recommend no "sneaking away" while your son is engaged in an activity. My child searches for me after I leave - wandering through the house, crying. If I say, "I'm leaving - I'll be back soon, I love you!" and then i go - he's a basketcase for a few minutes and then he recovers.
It sounds like your son's teachers are committed and have great communication with you. I'd encourage you to stick with and ride it out. I think your kiddo will learn to love his preschool.
Oh - if you don't have a copy of "The Kissing Hand" by Audrey Penn, get one! It's a wonderfully illustrated story about a little raccoon who is scared to leave his mom to go to school, and she reassures him and gives him a kiss in his palm to take with him. It's beautiful. We read it every night!
Let us know how things go!