Last week at ad:tech San Francisco, Google announced Multi-Channel Funnels in Google Analytics, a new feature that will show which channels your customers interacted with during the 30 days prior to converting or purchasing.

In online marketing, conversions and e-commerce transactions are credited to the last campaign, search, or ad that referred the visitor when he or she converted. But what role did prior website referrals, searches and ads play in that conversion? How much time passed between the visitor’s initial interest and his or her purchase? Multi-Channel Funnels will tell the complete story by providing cross channel reporting on the conversion funnel, showing marketers which digital channels customers interact with before purchase.

Update: As of August 24, 2011, Multi-Channel Funnels in Google Analytics are now available to everyone.