Opera, makers of the cross-platform Opera Browser, have announced the Opera Platform for mobile.
If I'm reading the docs right, the Opera Platform enables development of native S60 and Windows Mobile applications using HTML and JavaScript (and AJAX.) The platform also provides hooks back into native device APIs to access local services like PIM data (which I'm assuming is done using custom JavaScript calls.)
This may or may not be similar to the recent Openwave Mobile SDK (which I've heard about, but haven't seen in action) and may turn out to be a competitor to Macromedia Flashlite as well.
There has been much talk on the potential of "widgets" (ala Dashboard and Konfabulator) on mobile devices, and it would appear that we're now seeing the first entries into the mobile widget authoring market!