I am still catching my breath. Adobe has agreed to acquire Marketo for $4.75 billion. The deal is the biggest in Adobe’s history and a massive encore to the acquisition of Magento for a mere $1.7 billion in May. On the one hand, I find myself proud to be a B2B marketer — to think that helping folks like me be more successful is worth $4.75 billion. On the other hand, you’ve just gotta wonder about that number. My colleagues Joe Stanhope…