The answer depends...
Current industrial, ruggedized, devices normally still come with a QVGA screen (240x320).
There are now some ruggedized devices by Motorola and Intermec supporting a VGA screen (480x640).
I have seen many support calls where applications where designed for a fixed screen size of QVGA and now are run on VGA devices. I do not want to imagine what happens if a VGA application is run on a QVGA device.
So, best is to have your app scale with the screen.
If you are writing comapct framework application, scaling will be done automatically if design is done for QVGA and AutoscaleMode is set to DPI (default setting). The Compact Framework runtime will then scale your forms on VGA devices (see also HIRES_AWARE and Major Subsystem Version Number in below posts).
See also: http://www.hjgode.de/wp/2013/04/19/windows-mobile-6-5-changed-screen-geometry/ and http://www.hjgode.de/wp/2013/01/23/internet-explorer-mobile-qvga-web-site-do-not-scale-well-to-vga-screen/ and http://www.hjgode.de/wp/2011/09/05/remote-desktop-mobile-on-vga-devices-qvga-applications-do-not-scale-well/
If you are interested in a more flexible layout 'engine', see here: http://www.hjgode.de/wp/2010/07/17/mobile-development-using-layout-managers/
In the consumer area devices come with many different screen resolutions and there is no other way than using a layout manager to produce more or less fitting solutions.