Historically Mozilla spent quite a bit of energy promoting use of the "open Web" over proprietary platforms and non-standard browser extensions (IE6). This is still needed, but the landscape has shifted and I think our emphasis needs to change with it.
The platforms we need to worry about have changed a lot. Instead of WPF, Silverlight and Flash, the proprietary stacks competing for developers are now iOS and Android. Accordingly, the features the Web needs to catch up on are mobile focused. We need to be knocking down the barriers that make mobile app developers write native apps instead of Web apps (and we are!) and we need to be promoting the development and use of Web apps instead of native mobile apps. Demos that only work on desktop browsers are less important.
The open Web also has some interesting new platform competitors: platforms that build on (embrace and extend?) Web standards but take control of application delivery to create a vendor-controlled platform. The Chrome app store and the upcoming Windows 8 Metro app store are examples of this. I was very disappointed to see offline GMail and Google Calendar restricted to being Chrome apps. Even though Angry Birds works great in Firefox, its Chrome branding alone probably makes people think it only works in Chrome. To counter this we have to make sure that browser competition stays strong and offer developers browser-neutral Web app stores. Mozilla is working on these, of course :-). We also need to send a clear message that browser-specific app stores run counter to the open Web.
A less obvious form of platform competition is application developers targeting a single browser or browser engine. Google is explicitly telling its developers to target Chrome-only at first and support other browsers as an afterthought. That's understandable, but still disturbing. Also disturbing is that many mobile sites only target Webkit (sometimes implicitly by relying on Webkit bugs, more often explicitly by relying on -webkit-prefixed features). Many mobile developers, even developers at good places like Google, are reluctant to change this behavior. This is a huge problem for the open Web. We need an open-Web-standards campaign targeted at mobile Web developers. We need to be clear that apps working only a single browser engine, whichever engine that is, run counter to the open Web.
It's unfortunate that only Mozilla (and maybe Opera) of the major browser vendors has no vested interest in the success of a non-open-Web platform. I'm glad I work here.
One of the great things about the Web right now is the explosion of new features and standards for Web developers. However, we need to carefully distinguish good open standards from "open-washed" single-vendor initiatives. Not every proposed standard is good for the Web, even if it comes with an open-source implementation. Maciej Stachowiak points out a few Google projects --- VP8, SPDY, Pepper, and Native Client --- that, while they may be good ideas, fall short of true open standards to varying degrees. (The lack of a good spec for VP8 is an issue that we at Mozilla can and probably should address ourselves.) There are also cases where even though a good multi-vendor spec exists and some Web developers want it, the feature is not good for the Web and should be resisted. So I think when we promote the open Web we need to be very discerning about which specs we promote. Just because someone pushed out a draft spec with "CSS" (or "HTML" or "Web") in the name, and shipped a prefixed implementation, doesn't mean that that spec is, or should be, part of the open Web. People need to ask: is this feature good for the Web? is there a thorough draft spec that doesn't require reverse-engineering of an existing implementation? are there multiple implementations? is the spec actively edited with feedback from multiple vendors, and Web authors, being taken into account?
It's a challenging time. It's an exciting time. Despite the threats I mentioned, it's great to see massive investment in improvements in open Web technology. It's great to see Microsoft moving away from Silverlight towards a standards-based platform. We've won some battles, but the war for open Web standards is not over and we need to keep fighting it, on the right fronts.