Blackboard knows that their patent action is unconscionable and is open to challenge. But they didn't do it to becuse they thought it had merit - prior art demonstrates that the patent is not applicable. But they don't need to have the patent honoured -they can succeed at what they really wanted this action to do - scare the market and keep prospective proprietary systems at bay.
Institutions are naturally leary of litigation, and would choose to have sand kicked in their face rather than maybe, just maybe be involved in a legal fight with Blackboard. Blackboard may succeed in putting desire2learn out of business (a Canadian company) , and will succeed in scaring off any other company that is drawing up plans to enter the ed tech software arena. But I think Blackboard is going to lose on two fronts. The first is that some forward thinking institutions will think twice about tying into any proprietary system and will take a serious look at Moodle or sakai or Elgg (eg. Open University and Athabasca University already use Moodle). And the second is that Blackboard has through their actions, galvanized an opposition consisting of the educational blogosphere, educause and the open systems folks, and many fence sitting educators who now see open source as a possibility.
If Blackboard continues to push this patent action they will lose the respect and goodwill they have developed over the years. Blackboard would do well to settle out of court with d2l and let this patent action drift off into the twilight zone. Then maybe they can start acting as the leaders they could be rather than trying to stifle competition and innovation.