I've come across a few suggestions of "develop-once, deploy anywhere" mobile frameworks from other SO questions:
http://www.mosync.com
http://rhomobile.com
http://phonegap.com
I was wondering if there are other alternatives to these mobile frameworks. None of them have the ability to access call logs or hook into a phone's call events (I realize those aren't possible on iPhone).
There's Appcelerator Titanium Mobile for Android/iPhone, but I don't know if it can do what you're looking for, either.
The problem is that the ability you want is pretty specific to the device, so it is unlikely anyone will come up with a framework in the near future that supports it.
That said, PhoneGap supports adding any native code you desire, so you could do the bulk of the app in it and then add native code for the bits that are not supported. It's a lot easier than creating apps from scratch for each platform.
The Qt Mobility project is the only one with such functionality i think but i am not sure, more info at http://labs.trolltech.com/page/Projects/QtMobility
more info: http://qt.nokia.com/developer/new-qt-apis
platforms supported: http://qt.nokia.com/doc/qtmobility-1.0-tp/index.html#platform-compatability