"What's the hottest mortgage product today? . . . The 30-year fixed-rate mortgage"
and interestingly,
"Prior to the Great Depression, the typical mortgage contract had a maturity of less than 10 years, a loan-to-value ratio of about 50 percent"
From here:
http://www.bankrate.com/brm/news/mortgages/20071101_mortgage_basics_return_a1.asp