The Associated Press reported today that Sarah and Todd Palin have released their 2006 and 2007 tax returns.  The release concluded:

The McCain-Palin campaign had said the tax returns would be released Monday, but it suddenly put them out Friday afternoon — a time long used by government to reveal embarrassing news because few people watch TV or read newspapers Friday evening and Saturday.

Interestingly, Joe and Jill Biden also released tax returns on a Friday. In their case it was September 12.  The AP began its report:

Democratic vice presidential nominee Joe Biden and his wife on Friday released a decade of their personal financial records, showing a veteran U.S. senator who earned less than many of his congressional colleagues.

Oddly, no mention was made that Friday is "a time long used by government to reveal embarrassing news."