Not that your standard cable release is obsolete but Trigger Happy is an innovative cross platform mobile app that allows for easy camera control with phone, tablet or iPad. Born out of a Kickstarter campaign last year, the app, when combined with a three foot audio cable that is included with purchase, can fire most Nikon, Canon, Sony and Olympus DSLRs. It is now available and fulfilled by Amazon.
Trigger Happy functions as more than a simple shutter release as it features the ability for long exposures, a programmable intervalometer and HDR mode and time-lapse Bramping capabilities. Available here and in the App store and on Google Play, Trigger Happy can be a primary cable release or a nice easy backup solution in a gear emergency.