They've been discontinued because they're not customizable. Use the online character builder or power2ool.com to generate printable cards. For electronic cards, i4e on the iPhone or iplay4e for mobile browser provide excellent experiences.
The experiment of mass-produced power cards is considered to have failed when contrasted with customized power cards offered by various services. Therefore Wizards offers custom power cards via the character builder. While there are no official notifications, the new CB and the different focus on D&D Essentials and online Dragon made the utility of mass-printed power cards problematic.
Other sites, especially power2ool.com offer similar services without the character-building capability. I use power2ool in the RPG.SE game and am quite happy with it as both player and GM.
Given that you're looking for smartphone experience, for those with iphones I can recommend i4e. It is an excellent phone-based system (one that I use personally when playing) and developed by someone who is responsive to customer feedback (I gave him rather a lot). For 'droids, I'm less sure, but the iplay4e mobile experience isn't bad if you have a fast phone. (My Iphone 3g doesn't like it all that much.) The other downside to iplay4e is that it really does want you to have a .dnd4e sheet built by the character builder. i4e allows you to enter everything by hand, which as a pedagogic technique is quite effective.