In response to your first post:
Regarding the need for people to not speak of being a stream-winner: I have read suttas where Buddha specifically encourages lay practitioners to state that they are stream-winners when that is the case. In this respect I think you are encountering a cultural view which is a different issue. In my experience, you can say it all you want and most everyone won't here a word you say :-(
how would a person know for sure whether he is actually a Stream enterer?
If you are in contact with those who have been through it - that is probably the best way. Of course, you have to have some sense that they have not deceived themselves. Short of that, I think keep practicing, have patience (years), and see what happens.
It is quite possible to go through the functional equivalent of stream-entry and not have any knowledge of Buddhism, noble eight fold path, etc. It has happened to many people including myself. I went through stream-entry years before I knew anything about Buddhism, Suttas, etc. Even so, my experience was very much like it is described in the Suttas. So a little about that:
1. "Sakkaya ditti'- Existence of a self in the Five aggregates.
2. ''Vichikichcha'- Doubtfulness of the Buddha and his teachings.
3. ''Seelabbhatha paraamaasa'' - Belief on rites and rituals.
The first three fetters:
1) Self. So you have this experience - It will without a doubt convince you that you are not this body, thoughts, etc. After this experience, you will still get caught up in all the ego stuff - patterns of behaviour - but when you reflect on your stream-entry experience (aka 'direct perception of emptiness') you will keep coming back to 'I know this isn't so' - something like that.
2) Doubt. If you have been studying the suttas then you 'get' lots about suffering and other stuff the Buddha teaches - this is as a direct result of the stream-entry experience (insight) [If you haven't studied the suttas (my situation) you still 'get' lots about suffering (but you would describe it in your own language obviously)]. You know for sure that Buddha was not making this stuff up.
3) Rites and Rituals - The issue is really more general: You no longer believe that concepts, beliefs, etc. are going to get you out of this mess. You have directly seen the nature of samsara and know that these things are the brick and mortar of your prison.
Many people feel that fetters = defilements. Fetters are what link you (your conscious awareness) to a defilement (lets say anger), producing a sense of self. An analogy is a post (anger), a horse (your awareness), and a rope (the fetter). When the rope ties the horse to the post this is like you being bound up with anger. When the rope is cut then the post may or may not be there (there may or may not be anger for example) but the horse is not defined or constrained by it (you no longer create a sense of self in relation to it). There are suttas that clarify this - one I recall likening a fetter to a rabbit snare - but trying to figure this out from the suttas can be confusing. Fetters are tricky - you cannot actually cut them yourself because before they break you are not locate them and afterwards all you know is that something has changed in you.
In the suttas, jhana combines insight and tranquillity. Together they develop a sense of dispassion for conditioned experience and the mind inclines more and more toward stillness until it releases (stream entry). This is a common theme in the Suttas and describes my own experience of stream entry. I know that Daniel and others here have had different experiences - there may be many I suppose - but what is written in the Suttas does define at least one way stream-entry is experienced.
Yogis who are unaware of buddhas teachings are also capable of going into jhanas. But are they on the noble eightfold path? (The ONLY Path to Nirvana), most certainly not.
This, to me, is dogma. I think you need to consider that Buddha, Jesus, Mohammed, etc. all said something to the equivalent of this. Lots of people have gotten killed over this one. My experience now is so different (4th path) as compared to before that I don't think they were refering to their teachings or egoic sense of self - rather their statements are more like: 'Only through this process that I have come through could anyone arrive at this experience'.
-Chuck