Okay, first, I have to address Ebay bashers. I've bought and sold on Ebay for quite a while and done quite nicely. If you are careful, you will never be screwed over, and you won't lose money on a transaction.
Second, Ebay isn't going down like the Titanic. Q1 for Ebay they were up 35% in revenue growth. They also saw a 31% increase in registered users YOY. This is going to be a $5 billion dollar company merging powers with Yahoo. It's an announcement that should at least be taken somewhat seriously.
Finally, while I hate the "Ebay" ads just like everyone else, they work. Ebay is making some serious money, and very few of us have built a company that could show the sustained YOY growth that they have.
While I don't think this will kill Google's revenue, I do think this could be a decent dent. Definately worth noting the shift.
In all honesty, I think we are in the very infancy of the internet and related businesses and it will be quite a while before the markets really start to settle. We're still learning how to do things right, and new technologies are changing the shape of things on a daily basis.
Don't forget, Yahoo has one of the largest registered user bases on the internet, as does Ebay. I think that people should respect this a little more than they are.