Just got home after a very long day, was meant to be a short day but...well...
This was the day we planned to deploy the big site we've been developing for the past 8 months to its' final hosting environment. Unfortunately, the environment wasn't configured as had been requested, so I spent the day trying to come up with workarounds. Problem boled down to .NET Passport and its' wily ways. Essentially, Passport is able to run in two modes, Pre-production - where you make your own key and can use what is essentially a test mode for developing the functionality in  your site - good idea I think you'll agree!
Problem comes when you want to go live, basically Passport was developed with a single way of working in mind - you're meant to use one set of servers for test (Pre-prod) and another for live - you can only enter live when Microsoft have approved your site and you've paid your license fee (which is a LOT of cash!). However, catch is (and just show me where in the documentation it mentions this!), you can only have a Production OR a Pre-production  mode on a single server. Now you can have two keys for different sites, in fact you can have dozens, it's just that the entire Passport Manager system (which you install on your server) only runs in one mode or the other - the only indication of this can be seen in the grab below - apparently some fields being grey indicate that this change applies to the entire machne, not just this key! Talk about usability!

Now, I'm not saying Passport is a terrible idea which should be done away with, the next version of Passport is supposedly going to be based on Web Services and be much more compliant with the .NET way of doing things. Its' just the current version feels half baked (the documentation for C# for instance is frequently wrong). Don't belive me, go to http://www.passport.net then click on the developer link...useful huh! If you are developing using .NET Passport in C#, ignore the documentation, it's pretty much useless. You'll do yourself a favour (and possibly save your sanity) if you have a look here:

http://www.microsoft.com/downloads/details.aspx?FamilyID=910934cc-03ad-43e4-977e-235a06f7c3b5&DisplayLang=en  This is the Passport Proscriptive Architecture thing, it has all the code you need to use Passport. Otherwise just wait a few months until the usable version is released!

UPDATE: Yes, I know the passport link redirects...to be it just indicates the general lack of attention to the usability of this product (which again, you do have to pay THOUSANDS OF POUNDS to use)