Matt McGee recently posted on Cre8asite Forums asking how long a 302 redirect should stay in place -- because if it's there for too long, he is afraid that search engines will see the redirect as a permanent 301 redirect.
I almost blogged about this question on Search Engine Roundtable the day he asked that question, but I held off for more commentary, and the impatient Matt decided to bring the question to his blog.
Well, thanks Matt, but I was watching out for you. :)
In any event, moderator eKstreme writes in to say that it should be treated as temporary and if search engines didn't do so, they'd be breaking HTTP protocol.
The HTTP/1.1 specification says nothing about long-duration 302s being treated as permanent. As such, an behavior along these lines is actually breaking the standard. If any of the search engines actually behave like this, it would be the first time I hear of them breaking HTTP protocol. It's very unlikely they're doing this.
Does anyone have any better insight? Let's help Matt out!
And Matt, the following coverage on 301 vs. 302 redirects might also help you out.
Forum discussion continues at Cre8asite Forums.