Amiri font has been recognised by the Wikimedia Foundation for some time; it has been provided in the Web Fonts extensionn for some time and recently in an other bit of "read the whole article to get to the good news" it became part of a Wikimedia supported jQuery library for web fonts.
Google has also recognised the Amiri font; they make Amiri available through their "early access" program. Google supports multiple (freely licensed) Arabic fonts as web fonts. The biggest difference for me between the two programs is that the WMF library has your server provide the fonts while the Google offering has the fonts provided through the Google infrastructure.
Both Google and WMF support fonts for many scripts. The question is what they will do when the font has technical requirements that are more than usual.
Recently the Tuladha Jejeg font for the Javanese script was given a free license and the Wikimedia Foundation will assess if they will include it in their Web fontd extension. There may be a technical problem; it makes use of the SIL Graphite technology. The question is to what extend do browsers support this technology.
When Google is serious in supporting the rare scripts, the opportunity to support the Javanese script through the Tuladha Jejeg font may be reason enough to put some extra effort in enabling support for SIL Graphite.
<grin> One may hope for Google to do more good, we know they can</grin> <seriously> For the WMF there is hardly another option when they are to support Javanese </seriously>