Our friend Mark Lord over at Professional Engineering Publishing has a very interesting post up about what Google's new "Caffeine" search index might mean to publishers. Caffeine is designed to provide "fresher" results, and may affect how easy/difficult it is for users to discover your content. From the piece:

If you do a search [with Google Caffeine] you will see a lot more hits that are from news sites, video sites, images, respected sources and social media - so results from Twitter for instance. In the past the ranking of results would depend more simply on relevance and PageRank. But now Google want to make their content as current as possible, so if you have content that is on a slower refresh cycle you could suffer. 

So why is Caffeine of importance to publishers of scholarly journals? Well it could fundamentally change the search results that users of Google see. It's very likely that unless publishers keep pace with Google's changes they may find their websites attracting less traffic from Google.

Mark fleshes out the potential threats and opportunities on the PEP blog: http://acadblog.pepublishing.com/.