Le petit 't'

In expressions like 'neige-t-il' or 'y-a-t'il', what is the meaning of the 't'? Is it an abbreviation?

the "t" actually has no meaning! "y a-t-il" is an inversion of "il y a", meaning "there is". In French, there is an aspect called euphony, that is the harmonious flow of speech. Each word seems to flow to the next. In this example, which sounds nicer, y a-il? or y a-t-il? The "t" helps to get rid of the pause between "a" and "il". You can read more about French Euphony here: http://french.about.com/cs/pronunciation/a/euphony.htm