It didn't 'originate' in the Senate technically. The bill number refers the 'H.R.' meaning House of Representatives.
They basically took an existing House bill that had nothing to do with the bailout and sent it to the Senate.
The Senate then added an amendment that threw out the complete text of the original bill and added the bailout text.
This is what they voted on.
Scummy, I know - but that's the way the do things in Washington (and most states for that matter).
While I was reading the gutted H.R. 1424 I realized that the case was indeed that the Senate took the House’s bill and “amended” it. I hope the folks in the House defeat this bill, too.
The fact that the executive branch supports any of this exemplifies the meaning of “lame duck”. I love Bush for what he has done, but this is not very impressive.