Over the past several months there have been many dicussions concerning issues when using 301s. There are also issues with 302s but I won't address those in this topic.
The suggestion in the search engine marketing community when moving an old domain to a new domain is usually to use a 301 Moved Permanently. While this may be the correct method based on the protocol, it may not be the best option.
I am basing my statements above on personal experience and also a culmination of others who are having similar problems. It has been 113 days since I implemented a 301 from an old established domain to a new branded domain. All three of the majors (Google, Yahoo!, MSN) reacted very similarly in how they treated the 301s.
With Google, there was spidering immediately once the new site was launched. This was due to the 301 from old to new. There was a brief period where the new site appeared in its expected position. And then within 48 hours it was gone, not to be seen again until recently.
From that point forward, the old URI remained indexed and the client did appear for name searches. But, everything else was gone. We spent hours mapping old URIs to new URIs and double checked everything using various server tools prior to launch. This was by the book.
Yahoo! and MSN also maintained the old URI and were very slow to pick up the new URI. After the first of the year, that changed. Both Yahoo! and MSN have now purged the old URIs and have indexed the new ones.
To summarize this...
If you are going to move an old domain to a new domain, you may want to consider other options besides a 301. Figure out a way to keep the old site live while you make the slow transition from old to new. Don't abruptly stop everything to the old and expect it to transfer to the new. It just won't happen, at least in the 15-20 instances that I am aware of it hasn't.
I want to call this the new Kiss of Death in a search engine marketing campaign. That might be a little overboard. Expect to have some major downtime if you run into what I've seen and experienced first hand.
301s within an existing site are no problem. They are usually picked up within 48-96 hours (Google) and the old URI is dropped and replaced with the new URI. Yahoo! and MSN react similarly but take a little longer.
Anyone else care to share their 301 horror stories?