Well, thanks to software like PhoneGap and Javascript/CSS libraries like jQuery mobile (and many others), writing a "tablet app" is much the same as regular web development.
You can create an app with a native look and feel with pure HTML5/Javascript/CSS, and you can build it as native apps for iPhone and Android, and have it hosted on their app stores with the same codebase.
For platforms that doesn't offer app stores, you can just provide them with an URL to your app so they can use it in a regular browser (also using the same codebase). The development process can also be simplified, since you can do much of the development with a browser, compared to re-compiling for each iteration of development.
There are of course some applications that aren't suitable for being run in a browser, but in many cases you can, and being able to share codebase between all these platforms seems just great.
You can create an app with a native look and feel with pure HTML5/Javascript/CSS, and you can build it as native apps for iPhone and Android, and have it hosted on their app stores with the same codebase.
For platforms that doesn't offer app stores, you can just provide them with an URL to your app so they can use it in a regular browser (also using the same codebase). The development process can also be simplified, since you can do much of the development with a browser, compared to re-compiling for each iteration of development.
There are of course some applications that aren't suitable for being run in a browser, but in many cases you can, and being able to share codebase between all these platforms seems just great.
Arstechnica released their iPad app a month ago, based on HTML5/CSS/Javascript and built with PhoneGap, and they explain very well how and why they did it that way: http://arstechnica.com/apple/news/2010/11/introducing-the-ar...
I would definetely learn regular web development, and not lock myself down to a single platform. Especially with these cool tools like Phonegap.