Housing stocks got off the mat Thursday in anticipation of a government-backed plan to limit foreclosures. Among the biggest gainers in early afternoon action were Toll Brothers (TOL), the big luxury homebuilder, Countrywide (CFC), the biggest mortgage lender, and MBIA (MBI), the bond insurer whose shares plunged Wednesday after a rating agency said the firm may need to raise more capital as loan losses pile up. Other big gainers included MGIC (MTG), the mortgage insurer that lost $372 million last quarter as it wrote off an investment in a subprime mortgage venture, and Radian (RDN), whose merger with MGIC blew up after the market for mortgage-backed securities collapsed.

Two things are surprising about this rally. First, these stocks rose sharply last Friday, when word got out that Treasury Secretary Hank Paulson was trying to put together a package to ease the pain of sharply rising payments on adjustable rate mortgages, or ARMs. (Despite rising criticism of that plan, Fortune’s Adam Lashinsky, for one, still wants his frozen.) Second, it’s not at all clear that the Paulson plan — which is to be formally unveiled by the White House this afternoon — will really help borrowers, lenders or mortgage insurers all that much. Foreclosures are already at 20-year highs, going by numbers released Thursday, in a trend that’s certain to be costly for mortgage servicers and investors. And because so many homeowners overstretched to buy houses when prices were appreciating, many borrowers may not be able to continue paying even at their pre-reset interest rate.

Analyst Gary Gordon at Portales Partners says the lesson is that investors want to believe the bottom has been reached in financial and housing names. But he points out that today’s move amounts to the 10th substantial rally this year in the housing stocks, and each of the previous nine ended with the stocks below where they started. He says the poor fundamentals of the housing and mortgage markets make calls for a nascent recovery amount to “false hopes.” Sometimes, Gordon adds, referring to far-fetched hopes that housing will bottom soon, “It takes a while for people to absorb a new concept.”

Toll Brothers (TOL) slumped to its first quarterly loss in more than 20 years Thursday as buyers continue to retreat from the falling housing market. The luxury homebuilder lost $82 million, or 52 cents a share, for the fiscal fourth quarter ended Oct. 31, as sales fell 35 percent from a year ago. The company said latest-quarter results reflect a $314 million writedown of land holdings - bringing Toll’s total writedowns over the last five quarters, since U.S. house prices peaked, to $800 million. Even so, the company continues to own or hold options on more than 59,000 lots at a time when there’s a massive overhang of unsold existing homes - meaning more writedowns are surely on the way.

CEO Bob Toll was heard last month to blame media negativity, rather than sky-high home prices and overstretched consumers, for the housing bust. This time around, he is less interested in pointing the finger than in noting that this too shall pass. “It’s not a matter of if, but a matter of when, this oversupply is absorbed,” Toll said. “Then we shall return to better times. I believe those who wanted to buy but didn’t will kick themselves for their reticence, but the biggest hurdle for our clients right now is their concern about their ability to sell their old homes.” That hurdle’s not going to be cleared till prices fall a lot more.