The legal systems in the US and the UK are somewhat different on that matter, in the US I believe the "Prayer for relief" aspect mentioned in many documents is basically the equivilent to recovering costs. Maybe jadmperry would be kind enough to explain this part in a little more detail.
It's also why in the UK case IB was ordered to pay money into Escrow as over here the judge basically says you win or lose, and the losing party is responsible for paying the court costs for both parties involved, XenForo basically put an application forward saying if they lose, IB has no tangeable assets in the UK to pay that bill, so it would get lumped onto XenForo with no way to recover the money from IB.
Just a thought. If/when IB loose the US case, do you think they will still bother pursuing the UK case given their chances of winning would be very slim?