How can I use custom fonts in an HTML5 Canvas element?

I've thrown together a simple demo on jsfiddle here showing how to do this with @font-face: http://jsfiddle.net/zMKge/

Opera also has a simple tutorial on using <canvas>, including the text API.

CSS:

@font-face {
    font-family: 'KulminoituvaRegular';
    src: url('http://www.miketaylr.com/f/kulminoituva.ttf');
}

Javascript:

var ctx = document.getElementById('c').getContext('2d');
var kitty = new Image();
kitty.src = 'http://i954.photobucket.com/albums/ae30/rte148/891blog_keyboard_cat.gif';
kitty.onload = function(){
  ctx.drawImage(this, 0,0,this.width, this.height);
  ctx.font         = '68px KulminoituvaRegular';
  ctx.fillStyle = 'orangered';
  ctx.textBaseline = 'top';
  ctx.fillText  ('Keyboard Cat', 0, 270);
};

I have just answered this question here: Preload font HTML5, JS, Kinetic.js?

The essential part:

@font-face {
    font-family: 'myfont';
    src: url('myfont.eot');
    src: url('myfont.eot?#iefix') format('embedded-opentype'),
         url('myfont.woff') format('woff'),
         url('myfont.ttf') format('truetype'),
         url('myfont.svg#myfont') format('svg');
    font-weight: normal;
    font-style: normal;
}

It should not matter if you are using KineticJS or not, the only difference without KineticJS is that you would possibly create the Canvas element directly with HTML instead of using a div layer as container. After all KineticJS just creates a normal Canvas element in that container.