The issue was still occurring with DP5. Yet to test DP6.
I've just built a new OS X 10.10 Beta 2 and this had the same install problem; cured with the same darwin.iso method.
Fusion Tech Preview July 2014.
Alright folks, good news: we have identified the issue ("when installing tools via the VM > Install VMware Tools, the installation gets stuck") and we have fixed it internally. The current workarounds:
1) Connect the darwin.iso CD image to the VM manually
2) Copy darwin.iso inside the VM and open it inside the VM
are both valid until we release new bits with the fix.
A special thank you to everybody who helped narrow down the issue!