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.

• Web apps may develop a dangerous reputation because they bypass platform owner approval processes. The app store approval processes used for native apps allow platform vendors to institute thresholds of acceptable quality, security, privacy and other parameters that can then be validated and enforced through the approval process. As Web apps proliferate, some will undoubtedly give the genre a bad name. Independent app stores (such as Amazon’s) may emerge to fill the quality assurance gap.

• Web apps may use excessive bandwidth. Over time, developers are expected to become savvier with bandwidth, but the early days of casually constructed HTML5 apps may result in apps that do not leverage native platform features to minimize bandwidth.

For all the above reasons, native mobile application platforms are likely to remain the preferred approach to deliver application functionality for the majority of apps for some time to come. Web apps will, however, emerge as a second-tier alternative for delivering certain types of applications that do not, for example, require advanced device hardware, or that require user interfaces to be identical across devices. Web apps will also be leveraged heavily by mobile platforms such as BlackBerry and WebOS, which will find it easier to leverage the Web ecosystem of developers instead of creating a new one.

One important mobile platform that is expected to leverage HTML5 natively is Microsoft’s Windows 8, which is expected to ship in the second half of 2012.

Finally, Web apps may be attractive for enterprises as they begin to mobilize their application portfolios with an eye on a single strategic approach to target multiple mobile device platforms. Enterprises may well be mobilized into action by the arrival of new Windows 8 PCs.

All this is good news for Web developers who must learn HTML5 to harness the avalanche of new opportunities to come.

Al Hilwa is program director of application development software at IDC.