Talk of a housing bottom started sometime in October. Since then we've gotten more news on new and existing home sales to stoke talk of a housing bottom (We've also had home builders report some really lousy earnings reports). In addition, interest rates started to drop about that same time. Here's a chart of the 10-year Treasury from stockcharts.com
Rates have risen steadily since early December, largely because good economic news and public statements from various Fed governors dampened speculation of a rate cut in early 2007. As a result, the 10-year Treasury's interest rate is back near 4.84%. This was at least a non-restrictive interest level in October. We'll have to see if that still holds going forward.