Here's a very quick look at the Nokia N8's multitasking interface in comparison to the Omnia HD's.
The Omnia HD runs Symbian S60 5th edition and was announced on the 16th of February 2009, while the N8 runs Symbian^3 and was announced on the 27th of April 2010.
My opinion? I definitely prefer the Omnia HD's multitasking interface, despite the apparent similarities. The N8's multitasking view is a bit too limited. Using the Omnia HD's grid view, six applications can be displayed on one page. To do the same on the N8, the user must scroll through the list of applications.
I wonder why Nokia didn't just copy the N900's multitasking view and adapt it for the N8's lower resolution screen?