Captain Shrek
No idea. I really didn't pay much attention to combat. It's RTwP. I doubt they can make it worse and I doubt they can make it better. So, stamina, cooldowns, whatever, fine with me. Anyway, since you've asked, I'll go and read the update that mentioned stamina.
Edit:
In Project Eternity's combat, players need to be concerned with two elements of a character's vitality: Stamina and Health. The majority of damage a character takes is subtracted from his or her Stamina. Stamina represents how much general abuse a character can take before falling unconscious. Characters lose it quickly and regain it relatively rapidly, even without assistance. Soul-based abilities are able to help replenish or regenerate Stamina and are often used on the battlefield to turn the tide of combat. If a character hits 0 Stamina, he or she is knocked out. Intervention from another character can bring an unconscious character back into a fight.
For players, the Health of their party members is a tether that makes them consider how far they are willing to venture from a safe resting spot. Though Health is typically lost at a lower rate, when the PC or a companion hits 0 Health, he or she is maimed (in standard play) or killed (in Expert mode or as an option in standard play). Magic may help mitigate damage to Health and slow the tide, but once characters have died (in Expert mode), there is no known magic that can bring them back.
Is this all that's known about stamina or is there more?
The way it's described above, I don't like it at all. It sounds kind of convoluted. Or like a cheap way to please both camps. To hardcore gamers: don't worry guys, health is serious business, you can be maimed or even die! To Bio fans and casuals: we have great news for you! health-regen is in!