Dolby Digital, DD EX, DTS ES, THX, etc.

Okay, I apologize but I am getting lost here.
Could anyone please explain to me what are the latest developments regarding serious 8 channel sound formats? What are the official names of the standards?
What is DD EX? Is it DTS ES compatible? How does THX relate to EX? Are EX and ES standards to be taken seriously in private theaters?

Hope to learn from this guys ... thanks!