Finally found a solution:
http://lostechies.com/jimmybogard/2011/01/27/reloading-all-projects-with-vscommands/
Quoting from the site:
Quite often I’ll find myself working
in situations where multiple projects
have changed, and Visual Studio asks
to reload them, one at a time. This
happens when I’m working a lot with
source control, and doing things like
switching branches, performing merges,
or just integrating upstream changes.
I have to click “Reload” a million
times for each project that changed on
disk, and it’s quite annoying. On top
of that, VS forgets which files I have
open, so every file that I was working
on gets closed.I may be the last VS user to find out
about this, but a free lite version of
the VSCommands plugin is available on
the Visual Studio Gallery that does
just what I need – reload all changed
projects at once, preserving which
files I had open: