Something I have noticed recently, in many international forums (i.e. English-speaking with many non-native speakers, including SE), is the use of a capital "Y" in "You", especially in "Thank You": I would tend to believe this comes as an analogy with "I", or as a way of showing respect, but of course it might be completely random.
Is it something that has been "imported" by non-native speakers, or is it a trend in the English language which might eventually become a valid form?