Looks like it's part of the OS for the Venue. It is the Recent Apps page for the Venue (long press home key). If you look at the other images on the page you linked (Dell Venue Smartphone), it shows the Gallery and Bookmarks screens that look similar to the Recent Apps screen.

The confusion is because the Recent Apps screen on the page is in Japanese while the other two are in English. I found other photos via Google Image Search:

Japanese - Notice the Japanese character for Home next to the Home icon at the bottom of the screen. Looks like the one on the page you linked.

English - Looks like an identical screen, but in English.

 

No, I think it is part of the Venue's OS. HTC has Sense, Motorola has Blur, and most other phone makers do something to change the appearance of Android. Dell has "skinned" their Android phone to look like this.

If you wait long enough, someone may create a ROM that looks like the Venue's OS. It just depends on if a developer likes what they did with the Venue and wants it on their phone. Or someone may create an app that resembles the Venue's Recent App list, like LevelUp Studios created Beautiful Widgets to look like HTC Sense clock/weather widget.

All that being said, there are a LOT of weather widgets and apps in the Market. Both free and paid. Maybe there's something there you'll like even more!