Well yes. That is what it would suggest. Either shouting or very excited! I tend to use caps when I am excited. And my friends know this so I guess they would see it as me being excited rather than shouting. i think that when my friends do capital letters, it depends on the context and what we were talking about too! if I say something to upset someone then I suppose the capitals would look like shouting, otherwise it would be seen as shock or excitement too!
I think if the whole text is in capitals then it is considered shouting. I don't like seeing a whole text in caps as I think it is intimidating. It's different if you want to make a point like saying happy birthday cos you'd normally emphasise your voice when you do this anyway. Also if you make a distinction like Belindac says ( I love to read / I LOVE to read) these are totally acceptable but not when the whole lot is in caps as this definately comes across as shouting.
Yep, anytime someone uses capitals I always assume they are shouting and it does grate just a little bit. I know some people aren't aware that it is a way of shouting while typing but most people seem to. It can come across as quite aggressive too, not sure why exactly, maybe because the letters are so big compared to what everyone is doing. Personally I avoid using caps unless I mean to shout like when I type "happy birthday" to people etc.
I think in general, it is the written equivalent of shouting out if the whole piece is set in capitals, unless it was just a mistake in omitting to take the caps lock off. I would not hand write a note or a letter in capitals, so why type in caps unless it is a genuine mistake. Occasionally I may type a word or phrase in caps, just to emphasise on that particular word or phrase, but I never deliberately type out a whole piece in caps. I have occasionally visited online bingo sites, and the chat moderarators do actually ask people typing in caps not to shout, and if they continue they are "booted out" of the game. On the bingo sites it is considered not just as shouting, but as rude and offensive.