Even if Vonage cannot prevail in the courts, they may still have a saving grace. They have mentioned for a while how they are looking for a workaround to avoid infringing upon Verizon's patents. For a while, it didn't look so good, with even themselves stating the patents couldn't be avoided. There's a bit of backtracking going on now, though, and they claim they may have a workaround. In fact, they claim they are going to be rolling over to them over the next few weeks:

"We will begin rolling these workarounds out shortly, hopefully in the next few weeks, and we believe they will work,'' Chief Executive Officer Jeffrey Citron said on a conference call today, reported Bloomberg.
If they manage to find a proper fix, it still won't be the end of the story – Verizon likely will go after them for the years past, though they'll have much less ground to stand on then before. If Vonage does manage to make it out of the woods on this one, it will be a step in the right direction for the VoIP market, which many traditional phone providers loathe.