CNet blogged that while RIM is looking into open-sourcing, it is not about to happen. If at all.
The main issue is the business model. Apple has invigorated the mobile market with its innovative iPhone and other companies may find it difficult to keep up in the long run. Apple has indicated it plan on using it's $25 billion war-chest to put more distance between it and its competitors. I suppose they've got a point there. But even with open-souce, software aside, there is the hardware development that can't exactly be open sourced, right? Outsourcing may be a different matter but there is no short-cut around hardware development that each handset maker must do on their own.
What a successful open source community does bring is numbers. However, the danger is fragmentation that can occur. One of the initial concern for Android was just this. However, with a close eye on the project and a lot of support from Google, it will have a big chance of not only succeeding but avoid having different versions of Android running on twenty different phones. This is the same for Symbian.
So far, I don't see this happening to Android. It's likely Google will keep it on a very short leash. What will be interesting is to see how different various forms and inputs that will crop up as more handset makers develop for the Android. In time, Android will support multi-touch. If a developer creates an app that is optimized for multi-touch, how will phones that do no support such gestures be handicapped?
Regardless of concerns, the Google is likely very content with the reception Android has received. All it needs now are good phones to work with. We will have to see if Symbian is afforded the same kind of reception.
As for Apple, don't bet on it. In fact, Safari, based on Webkit, is an open-source project and that's as far as Cupertino will likely go for now.
Link of interest: CNet