What do Amazon Kindle, “The Financial Times” and Wal-Mart’s Vudu have in common? They are the first major content distribution services to bet on HTML5 for mobile Web apps. All three claimed that they were motivated by not having to pay Apple a 30% markup, as well as by the desire to avoid Apple’s restrictions on directly marketing content inside its apps.

What’s important about these three new Web apps is that they provide an early glimpse of how HTML5 can be used to build engaging mobile experiences that can rival native applications built with the mobile platform owner’s anointed programming language, framework and tools. These apps offer offline capabilities and provide a touch-optimized and highly responsive user interface that targets specific devices.

With strong support from all major desktop and mobile browsers effectively in the market by late fall, and improved developer tools such as the recently announced Adobe Edge, HTML5 is showing signs of very rapid adoption. HTML5 appeals to developers who dwell in the larger Web ecosystem that also encompasses JavaScript and other scripting languages, thus tapping a huge segment of ready developer skills.

Nevertheless, mobile developers should be aware that Web apps will not displace native apps in the short term for the major mobile platforms. Here are some of the limitations that HTML5 Web apps face today compared with native apps:

• There are currently no standards for supporting important mobile device components (such as cameras) in HTML5. As mobile platforms evolve rapidly, new hardware will constantly be introduced, requiring new APIs to be supported. While efforts are under way to standardize such APIs, it is doubtful that standard bodies can keep up with the pace of evolution of mobile devices and the native mobile application platforms.

• The limitations of the browser sandbox model make it difficult for HTML5 apps to access device data such as contacts or calendar elements, or participate in inter-application communication.

• Because their rationale is unified development across multiple devices, Web apps will find it difficult to comply with user-interface guidelines of specific mobile platforms and thus look congruent with the overall device experience. This may be less of an issue on some platforms that do not seek conformity, or for certain app categories that require an identical UI across platforms (e.g. games), or where content dominates the UI (e.g. books, magazines or videos).

• Web apps may be unsuitable for ISVs who do not have a marketing platform. Platform owners’ app stores provide a tremendous opportunity to market and monetize apps through a variety of discovery tools. This has proved to be an enabler for many new ISVs to enter the mobile app space on an equal playing field.