Google announced the release of Smart Lists, making automating list creation for the purpose of remarketing from within Google Analytics a much simpler process.
Smart Lists tap into the anonymized conversion data that Google collects from those sites that have opted into the program. Google uses visit duration, page depth, physical location, device, referrer and browser to predict the users most likely to convert when they return to a website. Google Analytics automatically manages the remarketing campaigns in AdWords for advertisers, updating the data daily based on the most recent data available.
For sites that use ecommerce conversion tracking in Analytics and have at least 500 monthly ecommerce transactions and 10,000 daily pageviews, the Smart List will automatically be "upgraded" to rely on the sites' own data rather than that of similar businesses. The list appears as [My Smart List] in the list builder.