For those not familiar, Ghostscript strictly defined is a PostScript interpreter and many programs use GS for PostScript conversions and import/export. Likewise, Scribus uses Ghostscript, sometimes using some of the most advanced features available only in newer versions.
With regard to Scribus, there are two major issues: Ghostscript is a kind of black box command line tool with sometimes obscure or difficult to understand switches. Accessing many of these is made much easier with GSview, noted later. The other is there have been some major improvements in the 8.x versions, especially with advanced PS3, PDF 1.4 features and high end printing features. The next section outlines a possible way to upgrade to the latest version, without breaking your existing CUPS/Foomatic/GIMP print setup.
While Ghostscript originates from a commercial company and is dual licensed, the Ghostscript developers are very OSS friendly and have been very helpful to the Scribus team, especially with documentation and learning some of the more esoteric features. Ghostscript is one of core building blocks of OSS software. It would be hard to imagine OSS software without it.
When speaking of "devices" in Ghostscript, this refers to a certain type of driver or software module which performs conversions or special types of PostScript processing.
The latest generation of GS will have a new ink jet driver rinkj, which has some new techniques for optimal printing with some ink jet printers. Plus, support for jpeg2000 aka jasper, for lossless jpeg compression and PDF 1.5. Also, there are new devices which will support many advanced pre-press and printing features. Scribus will be one of the first applications to take advantage of these improvements. Thus, we always encourage you to have the latest Ghostscript available for your system and encourage distributions to migrate to GPL Ghostscript 8.x.