It's a shirt; no, it's a sweater; no, it's a jacket.
Truth is, it's all of them.
The new Nike Innovation Cover-Up ($120) wears like a sweater and functions like a weather-resistant jacket but is light enough to feel like a shirt. The rib sleeves are something I especially like, and the nylon and spandex fabric not only helps protect you from the elements, they create a trim fit that allows for more flexibility and range of motion when combined with the practicality of the water-resistant body. (Not to mention, it will make you look better.)
It seems as though you're always compromising when you play golf; one item to keep you dry, one to keep you warm, one to keep you comfortable. To combine all of those things is truly innovative. It's also great for everyday use, and for layering with other apparel.
Staying warm and dry in one piece is the new trend; we've seen some similar jackets in the industry but this is taking it to the next level, and I would be surprised if more designers don't follow suit.