The most seats lost in the last 100 years was by the Republican in 1932 at 101. And, that was remarkable considering just two years before (a year after the stock market crash), the Republicans lost 51 seats. In the 1932 election, the Republicans had squandered a 100+ seat majority it enjoyed just four short years before, and had a deficit of 113.
It was because of those tremendous swings - which were the completely reflective of the reactionary nature that the Founders intended the House to have - that gerrymandering became as prevalent as it did. Politicians didn't want to have such volatility in the careers.
As it stands today, because of the industrial nature of professional politics, it makes it virtually impossible to have such explosives changes - like another 100 swing in the House. It's really too bad.
We’ll see what the landscape is like. 100 is definitely high, but the public is more angry than I’ve ever seen them. If things continue on their current course, 2010 could make ‘94 look like an easy time to have a D next to your name.
Anything can happen between now and the election though and don’t count out idiot Republicans doing everything they can to insure a loss.
Gerrymandering involves creating as many districts as possible with a comfortable margin for your party, putting as many of the opposition into a smaller number of districts with an overwhelmingly large margin. In most years this guarantees a majority for the party doing the gerrymandering.
In a blowout election many of the districts with a comfortable Dem margin will be won by Republicans. That is how the GOP won the California legislature in 1994.
The really big point is that the legislatures elected in 2010 will be the ones creating the gerrymanders. A blowout election in 2010 will result in heavily Republican Congresses and legislatures for the next decade.