The solution is simple, you want to have a button on a cell.
Just think about editor !
By extending the class dojox.grid.editors.AlwaysOn, the button will allways appear during the viewing of the grid.

Source code

dojo.provide("foo.Button");

dojo.require("dojox.grid._data.dijitEditors");
dojo.require("dijit.form.Button");

dojo.declare("foo.Button", dojox.grid.editors.AlwaysOn, {
_valueProp: 'cellValue',
constructor: function(inCell) {
this.text = this.text || this.cell.text;
this.deleteAfter = this.deleteAfter || this.cell.deleteAfter;

i am trying to recreate the effect seen on the martha stewart website (on the righthand side "also try" area. the left and right arrows move the div in side with a cool smooth slide). i can see they're using prototype, but i really like how dijit is easy to use and set up.