Right now, you can view the comments for a given step on a guide if you scroll down the page to see Comments at the bottom. If you click the Comment bubble next to a particular step, it will also scroll you down the page to the appropriate location.
I doubt we'll create expandable comment bubbles in the near future, but we're planning on making some changes that should improve your experience with comments and guide viewing in general:
* Right now, the viewing of comments can be turned on and off at the bottom of a guide. We're going to default this to always on, and we're going to remove the ability to not show comments.
* We're going to add in dynamic loading of comments as you scroll down the page, so that the initial portions of the page will load quickly, and your browser will only load the comments once you scroll down.
** After we implement dynamic loading of comments, we'll implement dynamic loading of steps, and we'll remove the paginated view from guides.