Things get quite confusing with GPL when trying to apply it to non-source-code assets, but general copyright law is fairly clear here.
TL:DR don't use the icons unless you're willing to release the code per GPL requirements, you might be able to work around the restrictions, but you'd be walking a legal and ethical edge.

By distributing the icons (whether embedded or separately) you are copying a copyrighted work, so you must comply with copyright restrictions for the icons.
Copyright restrictions mean you have no right to use the copyrighted assets (the icons) except under the conditions of a license (or fair use, which would not apply here).
The only license you have is the GPL.  If GPL doesn't apply, then you have no license and cannot, legally, use the icons.
If GPL does apply, then you must comply with all of it's terms, including the requirement to release all source code for any combined work under the same (GPL) terms.
If you package the icons with your application (in an RPM, ZIP, or any other mechanism) or create a practical linkage (this can be tricky) between your work and the icons, then your application becomes part of a combined work with the icons, and you would have to release the source code.

It's possible the original author(s) would be willing to offer an alternative license for the use of their work (the icons), but you would have to contact them and secure that license in order to use the icons in your application.

It is probably much easier to use CreativeCommons (attribution only) licensed icons instead, as that license (but avoid the NC or SA variants!) is intended to provide a broader field of use.
A quick Google search turns up (as one example, I haven't checked beyond a quick glance) the following list http://blog.sleeplessbeastie.eu/2012/10/04/free-icons-for-web-designers-under-a-cc-license/


On 11/16/2013 10:04 PM, Daniel Stasinski wrote:
> I'm curious about GPL2 with regard to images.
> 
> I have found a set of gif icons that I would like to include in a
> non-commercial closed source application.  Since the images themselves are
> not being modified and they not directly embedded in the app, would this be
> an acceptable use under GPL2 if I did not release the source for my app?
> I've read all the faqs and it's just not that clear to me.
> 
> Daniel
> 
> 
> 
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