I'm guessing that only the more recent Mac models with Bluetooth 4.0 will be able to use these new features but I can't find any accurate information on this.
Right now I'm using Yosemite and iOS 8.0.2 on a MacBookPro8,1 (without Bluetooth 4.0) and iPhone 5s. I can't seem to use the Handoff features.
On the Mac I've even enabled the feature but still not working
Best Answer
System Requirements
Handoff and Instant Hotspot
Handoff and Instant Hotspot are supported by the following Mac models, and require OS X Yosemite:
Handoff is supported by the following iOS devices and requires iOS 8. Instant Hotspot requires one of these iPhone or iPad devices with cellular connectivity and iOS 8.1. Instant Hotspot also requires Personal Hotspot service through your carrier.
Phone calling
Phone calling requires an iPhone with iOS 8 and an activated carrier plan. Phone calling works with any iOS device that supports iOS 8 and any Mac that supports Yosemite.
SMS
SMS requires an iPhone with iOS 8.1 and an activated carrier plan. SMS works with any iOS device with iOS 8.1, and any Mac that supports Yosemite.
http://support.apple.com/kb/HT6337