The 'new' one in the top picture has been around for years. Apple used to use it for their older PowerBooks. (Back when the Apple logo was the way up dictated by ergonomics, rather than the current superficial aesthetic-driven orientation.) My current IBM ThinkPad uses the exact same plug. (In fact I'm using an old Apple power cable with my ThinkPad right now.)
If Dell are moving in this direction, that's actually a positive step. My Dell Latitude D800 uses a bizarre three pronged setup that is essentially the standard 2-pin figure of 8 (which is ubiquitous here in the UK; I've never seen any of those other 2-pins you show) with the third pin in line with the other two, rather than stacked in the middle. I've never seen this on anything else. (Not even on Dell's other laptops!)
The 'standard' 3-prong connector is often described as a 'kettle lead' in the UK because almost all kettles use them. (Although strictly speaking, kettles required the high-current variety, which have a little notch cut into the flat edge in line with the earth pin. However, you can use the high-current leads in computers just fine.)
I've never seen a laptop that uses the 'standard' kettle lead. All the laptops I've used have either had the figure of 8 2-pin, the 'new' 3-pin you show here, or Dell's bizarreo Latitude-D800-only inline 3-pin.