There is a lot of confusion about GPL and how it applies, and people are usually scared about using GPL licenses server-side for no reason. Disclaimer: I am not a lawyer (but I did quite a lot of research back in the day on the subject), and this is my understanding of the problem.
People are usually scared about using GPL (both v2 or v3) libs in their server-side applications, because they think they’ll have the obligation to release the source code of the application under GPL if they do so, since it’s becoming derivative product and GPL acts like a virus.
GPL, however, requires you to release source code of derived product only if you distribute the software, and - also often important - only to people you distribute compiled version to. Of course you can release the source to general public, or people who you distributed source to can do it freely too, but you don’t have to put the app source code on your web site, unless you distribute the compiled version as well for everyone.
The common use case where it’s totally unjustified to fear of using GPL libraries (server-side) is when you are building application for yourself, or you are a contractor building application to your customer. Take any GPL library (server-side), build your app around it, and you don’t have to distribute the sources under GPL if you never distribute the app. If people just interact with the app over network, you are still good because you are not distributing the app in any form to them.
Being able to use GPL-licensed libraries in closed-source products, as long as they happily run on your servers and not on clients, is an obvious loophole. FSF patched the loophole with release of AGPL license. This license is precisely like GPL, but says you have to distribute the source code of your app to also people interacting with the application over network. So, you can’t just grab AGPL-licensed library and use it within your backend system freely, something you can do with GPL.
As far as your original question go, I don’t think it’s any different using BEAM or linking library to program with C / ld on system level. There probably is no loophole there that you can exploit. But you may be just OK to use GPL library anyway because you are not distributing the software at all.