Apple Insider is reporting that iPhone developers have been contacted by Apple and asked:
enter up to 255 characters worth of keywords, separated by commas, which will be used for search in the App Store on the iPhone and iPod touch.
They're told this must be completed via iTunes Connect "as soon as possible so your application can continue to be successfully located on the App Store". What, if any measures are in place to prevent more ethically challenged developers from misappropriating key words (i.e. using names of competing products or unrelated yet popular terms) remains to be revealed.
Additionally, Apple Insider says search results have improved in general, a query for "EA" now returning 18 results for Electronic Arts games rather than previous results that included unrelated games using an abbreviation for "each".