Very nice utility. The "Open in New Group" context menu item strikes me as redundant, as you can choose "New Group" from the list of options on the "Open in Group" submenu; but that's a minor concern that's easily rectified by a decent context menu editor plugin. And other than that, I have no complaints.
This is going to make tab groups much more useful to me.
panolink seems not work in firefox under Linux (ubuntu 12.04). When I click right button on a link, I only see menu like this : http://postimage.org/image/oa5hbmvwt/ And it also screwed up my favorite addon : Tree Style Tab