Redirect to appropriate language - 301, 302 or other?

Which HTTP status code is best to redirect to a language specific version?

[simonwheatley]

Several of our sites have language specific versions, each language existing as a group of pages in a sub directory (e.g. "/en/", "/fr/", etc). When a visitor arrives at the site root (e.g. http://www.example.com/), we examine their browsers headers to see which languages [w3.org] they will accept, and then redirect them to an appropriate homepage. At the moment we're using a 302 Found [w3.org] status code in the redirection, as the place they are redirected to is temporary, based on (a) their accepted languages and (b) the current default language set in the site.

My problem is this: I have seen a lot of worrying about the effect of a 302 redirect on pagerank. Does 302 Found seem the best code to use, based on both Search Engine reaction and best practice according to the specs [w3.org]?

[DanA]

Redirecting according to the accepted language is not reliable.
As all bots do not set this parameter what happens?
I would use a silent redirect (with implicit code 200) and allow the user to switch to his prefered langage.

[simonwheatley]

If the language is not set, for whatever reason, the default language is used; i.e. the redirect can never fail.

[DanA]

Then most/major search engine bots will never see your redirection.
If you want to have all your languages indexed, you should have links to your translated pages.

[simonwheatley]

(I didn't mention this, as my initial question related to the status code of the initial redirection: on each page there is a list of links to other language equivalents of the page.)