1. When I use a Web app, it will be much faster, and more responsive
2. Microsoft and Adobe should be scared, as JS may just prove to be the true open-source competitor to Silverlight and AIR.
3. It will pave the way for more advanced, cross-platform Web apps.
4. Hopefully, as the speed difference between old and new browsers becomes more apparent, it will speed up the switchover from the horrors of IE6.  New apps will start to support IE6 less and less, as the performance hit will be unacceptable.
5. It could help attempts to piggyback certain technologies that Microsoft will probably never support (such as Canvas), onto IE.  Of course, this assumes that MS keeps up with the curve regarding JS performance.

And on a completely unrelated note, I found a cool page that beautifully sums up the options for IE when it comes to exploiting CSS hacks.  Whilst I knew most of the hacks on the page, this inline rule was quite interesting:

style=”*background:red!important;background:white!important;background:blue;”

The first background rule applies to IE7 only, the second to all other (more advanced) browsers, and the last one to IE6 only.  While inline CSS is not good for obvious reasons, I have found this hack to be quick and useful when restricted by bad design in some of our older sites.

Edit: This can also be used in external CSS files, as shown by this neat tutorial.  Furthermore, it shows that we can combine the star hack (applies to IE6 and 7) with the underscore hack (applies only to IE6), to produce a more streamlined version of this style attribute:

style=”*background:red;background:white;_background:blue;”

This is the first speed comparison of the new native JavaScript GetElementsByClassName functionality which is built into what will become Firefox 3. Very impressive, it should mean Fx3 will actually feel significantly faster when poking around sites, especially those with lots of JS.

Picture from the above link:

On a side note, I’m very impressed with WordPress so far, it’s all very well laid out, nice and intuitive. You can edit anything you want so eventually I’ll be hacking up a theme and hopefully integrating the blog with the rest of the (not yet existent) site. Oh, and the Dreamhost installation really was only one click!