One thing I've noticed. The code you're using turns the info balloon on by default, and the user can close it (click the X), but once they've closed it, they cannot reopen it by just clicking on the marker. They'd have to reload the page.
The code I picked up and am currently using (also now shown on my blog at www.dougjoseph.net) allows the marker's info balloon to be opened and closed by clicking on the marker.
Now if I just get the two combined. I want to have it on by default, and still be toggle-able by clicking on the marker.
I have not really tried very hard yet. I may look into it now. Last night I was foggy brained at the wee hours of the morning.