Perhaps I'm embittered after too much DailyWTF reading - there are a lot of idiots in our trade.
I wish it were true that every programmer, laid off in the recession, would seek to use his free time in a way that contributes to society - or at least to his own career growth. Sadly, this won't be the case; many will spend the next year watching TV and raiding dungeons, and not learn a thing.
A laid-off person needs to consider his future. Open Source participation is one of the best ways to ensure that, when the depression finally ends, such a person can still be considered a programmer.
Likely, some of those who have lost their jobs will moan that they don't have time to work on open-source projects; they'll move into their parents' basements, read job postings on Craigslist and send off a few dozen resumes each day, then spend the rest of their time playing World of Warcraft.
These people are losers. They weren't going to work on open-source projects anyway, so a recession and layoff doesn't make a bit of difference to their usefulness to the world. It just gives them more time for World of Warcraft.
For the rest of us, though, a layoff would be an opportunity to learn and to create. Job-hunting does not take eight hours a day - especially in a weakened job market, when few interviews are being granted. Does anyone really expect to go to four interviews a day? If things really tank, you'll be lucky to get one or two interviews a week. Mailing out resumes and reading advertisements doesn't take more than a few hours a day. What is a laid-off programmer going to do with the rest of the day?
The good ones will still be programming. Learn a new language or framework; study for certifications; work on an open-source project. All of these things will make the person more marketable.
(There are exceptions, of course. People with no savings and no family or friends who they can move in with might have to work twelve hours a day slinging hamburgers.)
When the job market improves, what will you say to a hiring manager at an interview about the missing year on your resume? "I learned Ruby and Haskell, and contributed Feature X to Project Y" or "I sent out lots of resumes and no one was hiring. But I got my Arch-Druid to level 80!"?
The bigger the theory the better.