So I downloaded and tested out Coda a little bit today. My initial impression is that I’m very impressed. It could be the new standard. A few like Alex King point out that it uses Safari as the default engine. I don’t think that’s so bad. Nothing stops you from using 2 windows one being Firefox (obviously running Firebug). I think the editor itself is rather well polished and very refined. The use of Bonjour to allow for collaboration makes it perfect for multi-developer environments. And yes, you can have more than two developers collaborating in 1 document.
My typical workflow is very abrupt. I tend to have Firefox, IE, and an IDE open at all times when coding pages. Not to mention a KVM switch to go between platforms. This still consolidates several things, and with a much nicer UI.
I’ll need to try it (for actual development purposes) for a few days before I could tell if it really works as well I hope. Panic is one of my favorite Mac developers. Really well polished products are their specialty.