[mathias_10gen]

The defualt mapping of Y is arguably broken since it doesn't follow the normal vi conventions. I have these lines in my .vimrc to "fix" it:

    "make shift Y behave like shift-[cd] (copy to end of line)
    nnoremap Y y$

[graywh]

Y being a synonym for yy is from vi. What you mean to say is that it doesn't fit the pattern D/dd and C/cc present.