One of the distinctive features of canvas is the sticker tray in the upper left of the page.
When you use canvas, you drag and drop these stickers onto images to recognize great posts. You also drag and drop the stickers to share on social media services, and to do other things in canvas (like remix). The stickers are the key engagement gestures in canvas.
So it makes sense that the canvas bookmarklet would maintain these engagement gestures outside of the canvas service. Here's a screenshot of the canvas bookmarklet in action on the NY Times website:
If you are a Yankee/A-Rod hater like me, how can you resist adding a #1 sticker to that image?
If you want to add the canvas bookmarklet to your browswer, you can get it here.