I've been busy playing with my new iPad 2 for the past couple of weeks. When I first connected it with iTunes, it transferred over all my hundreds of iPhone apps.
I noticed right away that these fell into two categories. Some apps open in a small window, slightly larger than the iPhone screen, with a "2X" button that enlarges it to fill most, but not all, of the screen, but generally making the graphics blurry and pixelated with elements that are not formatted for that size. Other apps are formatted for the iPad and fill the whole screen. The latter are indicated by a plus sign on their purchase buttons in the app store, and are called "universal apps", meaning that they are designed to work on all iOS devices, so that they are formatted for both iPhone and iPad. I also downloaded a bunch of iPad apps, which do not run at all on iPhones, although almost all iPhone apps will run on an iPad, even if not designed for it.
It seems that there are hardly any decimal/metric time apps designed for the iPad. I could find no universal decimal time apps. However, ecce, maker of the MetricClock and MetricClockFree apps for the iPhone, also now makes iPad only versions of these apps. However, since they are separate apps, you have to pay twice to get both the iPhone and iPad versions of the paid apps, although these are only $0.99, or you can just get the free versions with ads and fewer feartures. That's a better deal than some other apps, such as SkyFire, which charges $2.99 for their iPhone app and another $4.99 if you also want it on the iPad. (I'm using the iPhone version on my iPad, which looks crappy, but I only use it to convert Flash videos.)
On Wednesday (55657) ecce updated the MetricClock for iPad Free app to version 1.4, adding the ability to use backgrounds from your camera roll, and set the clock color. When I updated to the new version, my clock disappeared, but after I deleted and downloaded it again, it worked fine.
The only other decimal time iPad app I could find is Julian Date Converter, which is the iPad version of Julian Date Calculator for iPhone. This app, which costs a dollar more at $1.99, takes advantage of the larger screen by showing twelve different decimal times at once, while the iPhone version only shows the Julian Date and one other at a time. The iPad version includes one decimal time format that the iPhone one does not, GPS Time, and also displays the sidereal time and longitude, and also has the feature to "lock to UTC", which keeps all the times synchronized with the current time, incremented once a second.