Allegra coincided with an increase in hijack problems. Suddenly, long-established white-hat sites tanked. They were replaced by underdogs. If anyone has been able to determine specific Allegra algorithm changes, they haven't shared the information with me.
Could this monumental update actually be little more than a Google glitch? In its quest for the planet's biggest index, Google has thrown in everything that vaguely resembles a URL.
www.site.com and www.%20.com? Sure, throw them both in the index.
www.site.com, www.site.com/index and www.site.com/1? Right, chuck 'em all in the index.
A spammy old site with 950,000 outdated redirects that haven't been cached for 8 months? Excellent! The more the better!
Index them all and let the duplication filter sort them out. That seems to be the most significant "algorithm change" this year. Could it be that we are wasting our time trying to figure out what the latest algorithm tweaks are? Maybe we should just spend our days doing site: and allinurl: searches. These days, the winners are the sites that don't get jacked.