In a first of its kind feature on any mobile OS platform, Blackberry is introducing a Safe Mode function starting with RIM OS 4.6.1 that will hopefully help you avoid formatting the smartphone due to software failures. The first phone to feature this function would be the Blackberry Javelin.

The Safe Mode can be invoked by pressing the escape key during phone start up. If successfull, you will get a message:

Your device is currently in Safe Mode. Your device starts in Safe Mode if you hold the Escape key during startup. To remain in Safe Mode, click OK. To exit Safe Mode, click Reset.

There are no details as to what the Safe Mode is actually capable of and if it will behave the same way as Windows (with all third party services disabled) but it is definitely an innovative feature that will be beneficial and save time by not formatting the device.