One 10,000 lb gorilla we have been starting to tackle is mobile web applications. Now, there are a number of methods to go about this, but there are two basic paths:

1) Use simple HTML and mobile CSS to try and craft the same page to the mobile browser.
2) Build a separate mobile application, generally riding upon the core logic of the main web application.

I think both have merits and should be explored, but we have fallen squarely in school number two. The main reasons for this are:

1) Mobile CSS support is spotty at best.
2) Mobile users needs are different and you really do want to target them with different content and services.
3) The mobile browsing experience is so different that re-crafting even the best-thought-out of pages is very difficult. In many ways it is alot easier to just provide a different version.
4) Really applies to our systems, but I am generally dealing with things well-enough engineered to allow one to put a different UI layer on them without too much additional effort.

So, how are you all building applications in the mobile era? What is the strategy? How are you testing them? And has it been worth the effort?