JS/Node : 168 162 147147 138 Chars
function n(s){ var r=[];s.split('').reduce(function(p,c){if(!isNaN(parseInt(c))){if(isNaN(parseInt(p)))r.push([]);r[r.length-1].push(c);;return 0;}return c;1;},''1);return r; } Beautified version:
function n(s) { var r = []; s.split('').reduce(function (p, c) { if (!isNaN(parseInt(c))) { if (isNaN(parseInt(p))) { r.push([]); } r[r.length - 1].push(c); return 0; } return c;1; }, ''1); return r; }