When in insert mode, Ctrl-og$ works as expected
going to the character AFTER the last one.
But Ctrl-o:normal g$ doesn't go to after last char
So it seems to be a bug, which I worked around with the
following patch.

I noticed this when remapping the "end" key so that
it went to "end of screen" before "end of line".
When in insert mode this would not work as expected.
See function End() in http://www.pixelbeat.org/settings/.vimrc

Update: Though the problem was acknowledged the fix
was rejected because g$ has the additional functionality
(only documented in vim 6.3) that after doing g$, subsequent
vertical scrolling never goes beyond the current screen col, rather
than "sticking" to eol like $ does. I really don't see
why one would want that however?
The problem could be fixed by adding another state
variable, but this would be messy.

diff -ru vim-7.0023/src/normal.c vim-7.0023-pb/src/normal.c
--- vim-7.0023/src/normal.c	2004-11-18 09:34:23.000000000 +0000
+++ vim-7.0023-pb/src/normal.c	2004-12-21 19:16:06.000000000 +0000
@@ -7341,8 +7341,13 @@
 	    else
 	    {
 		i = curwin->w_leftcol + W_WIDTH(curwin) - col_off - 1;
-		coladvance((colnr_T)i);
-		curwin->w_set_curswant = TRUE;
+		if (i < W_WIDTH(curwin)) {
+		    curwin->w_curswant = MAXCOL;
+		    coladvance((colnr_T)i);
+		} else {
+		    coladvance((colnr_T)i);
+		    curwin->w_set_curswant = TRUE;
+		}
 	    }
 	}
 	break;