Expectations .............

I dont understand the atttitude of Americans. They give so much importance to weekends , leisure etc, but expect us to come and work on weekends. This week I have received number of mails enquiring whether I would come and work on weekend because they want to release a product. Its a different story that the release has been delayed but who is responsible for it.
On top of that yesterday in telecon they asked that since one of the fellow is coming late to office in US would anyone of us be around in the office when he comes in which would have been around 2130 IST.
In my three years of assoication with this client , I have noticed that many people working in client's office have been going on vacation during critical release times Then how do they expect us to work on weekends.