Just coming to light now, as reported by the Patently Apple blog and now making the rounds, is this patent for a "Tunable Shock Mount with Micro Inflatable Bladder" that, unlike our somewhat silly suggestion, is more sensibly placed inside the phone:
Apple's patent FIG. 5 shows a housing and a cover glass in cross sectional view having a tunable shock mount 505 disposed there between. The tunable shock mount could comprise of an inflatable bladder 506 filled with a fluid 507. Tuning could be done in various ways such as by selection of materials for the bladder and fluid, and by varying an amount of inflation. Hmm, think of it as a form of air-bag for portable devices.
Unsurprisingly, there's no word on whether this particular invention will ever see the light of day.