今天看到一篇关于iPhone的文章，让我很震惊。
用户可以使用iPhone App来替代车钥匙。
如果这个真的可以实现，或者说是普及，那我们以后口袋里装的东西会越来越少。
设想一下，移动支付现在已经在慢慢普及，以后我们口袋里装的东西将会只有一部iPhone。
下表为iPhone发展过程中的里程碑数据：
| July 11, 2008 | 500 | 0 |
| July 14, 2008 | 800 | 10,000,000 |
| September 9, 2008 | 3,000 | 100,000,000 |
| October 22, 2008 | 7,500 | 200,000,000 |
| December 5, 2008 | 10,000 | 300,000,000 |
| January 16, 2009 | 15,000 | 500,000,000 |
| March 17, 2009 | 25,000 | 800,000,000 |
| April 23, 2009 | 35,000 | 1,000,000,000 |
| June 8, 2009 | 50,000 | 1,000,000,000+ |
| July 11, 2009 | 55,000 | 1,000,000,000+ |
| July 14, 2009 | 65,000 | 1,500,000,000 |
| September 9, 2009 | 75,000 | 1,800,000,000 |
| September 28, 2009 | 85,000 | 2,000,000,000 |
数据来源：Wikipedia