The accepted solution gave me some issues (clicking on the '.popup-marker' element of the opened popover made the popovers not work afterwards). I came up with this other solution that works perfectly for me and it's quite simple (I'm using Bootstrap 2.3.1):
$('.popup-marker').popover({
html: true,
trigger: 'manual'
}).click(function(e) {
$('.popup-marker').not(this).popover('hide');
$(this).popover('toggle');
});
$(document).click(function(e) {
if (!$(e.target).is('.popup-marker, .popover-title, .popover-content')) {
$('.popup-marker').popover('hide');
}
});
UPDATE: This code works with Bootstrap 3 as well!