Two months at my place. Although short notice periods are good when you want to leave, they are not too good if you've been made redundant. I've found in the past that one month is'nt really long enough to find the job you really want. Most companies take 2-3 weeks to get back to you after your initial contact, and by the time you've gone through the interviews, medical etc you are living off your savings.
2-3 months seems about right to me.