Paid Apps include PrinterShare for iPhone and Android and the app will search for discoverable ePrint enabled printers. The free version allows you to print a test page, print via Google Cloud Print and print 20 pages remotely before requiring the full version which is $14.95. PrintCentral andPrintHub are iPhone only apps which will print to compatible printers remotely via wi-fi or 3G/4G network. PrintCentral is $7.49 while PrintHub is a mere $0.99 from iTunes.
Free Apps available include HP ePrint which will work with HP printers and also with printers that have HP compatible modes. PrinterOn is available for iPhone and Android and will search for discoverable ePrint enabled printers and public PrinterOn printing locations. Handy for printing boarding passes, movie tickets etc. while out and about.