A lot of people have released their apps to the market here, what are the things you need to take care of before releasing your app to the market, there was also a problem faced by someone who was having trouble updating his app in the market because he did not save the key?? Is this key available in the android Developer account and how to generate it??. Please share your experiences here
All the steps are described in detail in the "Publishing" section of the developer docs: http://developer.android.com/guide/index.html. Yes, you will not be able to update an app without the key; I'm not sure how/why that would happen, the docs are very specific about the need to keep it.