Looking from developer's perspective, developing for mobiles is not always that easy. If you're mobile web developer, you always have to test your work on many mobile browsers. The Mobile Web Test Suites Working Group has released a set of tests that assess the compatibility of mobile browsers with well-established, current and brand new Web technologies. The test (in the same spirit as the ACID tests) combines in a single page tests for 12 Web technologies. The latest version (1.41) has some improvements over April release. The source code is also available, so one can check how everything is tested.

And the results... are really different for every mobile browser - this applies also to mobile browsers based on "the same" WebKit open source browser engine (AFAIK, WebKit engine powers S60 3rd+, S40 6th+, Android platform and Apple devices, so it can be said that it dominates the 'mobile web') - see the gallery of screenshots for the first version of Web Compatibility Test for Mobile Browsers and the latest version. No mobile browser has passed all the tests so far, but I hope this will change in the near future.

The results for S60 SDK browsers (WebKit based):

As can be seen, there's still room for improvements in some areas (tests: 6, 7, 9, 12, 13, 14, 16). Will upcoming S60 5th edition be even better?

The test is available at http://dev.w3.org/2008/mobile-test/test.html
QR code for quick access: