Some tips from the article:
For mixing and creaming, butter should be about 65 degrees: cold to the touch but warm enough to spread. Just three degrees warmer, at 68 degrees, it begins to melt.I'm already looking forward to making some cookies soon.
For clean edges on cookies and for even baking, doughs and batters should stay cold — place them in the freezer when the mixing bowl seems to be warming up. And just before baking, cookies should be very well chilled, or even frozen hard.
The best way to get frozen or refrigerated butter ready for creaming is to cut it into chunks. (Never use a microwave: it will melt it, even though it will look solid.) When the butter is still cold, but takes the imprint of a finger when gently pressed, it is ready to be creamed.
The article talks about the variety of butters available to the home baker. I can't think of more than a few in our local stores: the store brand, one bigger brand, and maybe something from Lactancia. Where are all the artisan butters? Is it a function of our dairy board/milk quota system? We're experiencing a flourishing of small cheese-makers in BC, but so far I haven't seen anything similar in the world of butter.