Pelosi says we can still blame Bush. I think she's right. But the point isn't to blame Bush and therefore deflect responsibility from the Obama administration.
The point is Obama gets the blame for what he inherited from the Bush administration. When Obama took office, our country collapsed in many different ways.
Obama has done nothing but clean up one disaster after another. The financial meltdown clearly was caused by the lack of government oversight.
Keeping up with the Joneses also helped lead to the meltdown. If mortgage brokers were required to ask for proof of income to buy a house, we wouldn't be where we are today.
Obama hasn't been in office long enough to cause any of the problems we're seeing. Again, the point isn't to blame Bush. I think every president does the best he or she (someday) can. Some are more competent than others.
What good does it do to place blame? It doesn't solve any problem. But Obama shouldn't be blamed for what happened on Bush's watch.