I doubt it will natively, but through a third party app like RunKeeper I see no reason why not. Since currently the apps are tied to the iPhone, it would be connected to the iPhone anyways. However when they do allow native apps it stands to reason it should work, depending on the level of access the API gives to bluetooth devices, interesting question.
There have been reviews that say the watch is just as accurate as a chest strap, and reviews that say it isn't, so we probably won't know until we get more people testing. One review said it could connect to a Bluetooth chest strap, and one of the guided tour videos showed a section for Bluetooth medical devices (or something like that, don't remember the exact wording) when connecting a Bluetooth headset, so I think it's pretty likely that it will work.
If youre not able to get a consistent reading because of any of these factors, you can connect your Apple Watch wirelessly to external heart rate monitors such as Bluetooth chest straps.