Moving Web pages that have been indexed by search engines to a new URL via a 301 permanent redirect can cause serious dips in traffic once the search engines discover that the old page has moved. This is a headache that must be planned for whenever anyone considers changing the addresses of their Web pages, for whatever reason.
Barry Schwartz at Search Engine Roundtable last week highlighted a discussion at Google Groups in which Google's Adam Lasnik claimed that it only takes them a "couple of weeks for things to smooth out."
Unfortunately, although Google seems to be able to index pages within a few weeks, the past rankings for those pages are not updated in any time close to that, especially for competitive terms, without some additional effort. The primary method to speed this process seems to be gaining links from authority sites to the new URL, in a rapid fashion. Funny because that also seems to be the way out of what some call the fictional Google Sandbox.
The "trick" often used in order to try to lessen the severity of the old pages' loss of rankings is to employ a 302 redirect instead. This causes Google to keep the listing of the previous page within its index, and often in the same position within the rankings.
Some SEO's recommend using this tactic while "building up value" of the new pages through the form of new links that lead to the new URL. Although I have personally seen this work, I would recommend using 301s right away for all pages. It is nice to do this "off-season" if you are a seasonal kind of business, but unfortunately that isn't the case for every one.
I have always hoped to find a larger sample of case studies which show that Google can perform faster than what people consistently forecast as 3 months before original rankings are regained, if ever. Unfortunately, according to our engineers, the clients we have worked with have rarely seen this rapidity in bounce-back-ability. I asked Barry who agreed that 3 months was much closer to the norm.
So will Google allow users of the Webmaster Central portal to maybe jump line when it comes to regaining lost rankings due to URL rewrite or move? Will its algorithm ever speed this process out or will it stay like this to help avoid accidentally ranking pages which have considerable content changes.
Either way, moving to new URLs is something that will cause headaches no matter what, it seems. Everyone involved with the Web site should know that before the redirects are implemented, and other means of driving traffic to the pages should be considered as a top gap. These means include, but are not limited to the use of Paid Search, traditional marketing, as well as banner placement on well-trafficked sites.