Mac: http://s3.amazonaws.com/voicebeta-secondlife-com/SecondLife_1_17_0_110_VOICEBETA.dmg
No Linux -

I had a problem with the Windows download links but I think the above links will work. I didn't test the mac link.
Release Notes 1.17.0.110
Release Notes for Second Life 1.17.0(110) June 8, 2007
=====================================
New Features:
* Direct one-to-one voice chat is now available. This enables residents to initiate voice calls with just one other person, instead of groups. This is accessed via the Communicate button and the ChatterBox.
* Per-parcel voice settings are now available. Parcels can be set to use the same spatial voice chat channel as surrounding areas, use private per-parcel channels, or have spatial voice chat disabled.
Known Issues
* Though rare, proximal or "spatial" voice chat may not be available in all regions for which it is enabled. It works properly in most regions but there are occasional exceptions. This will be fixed in the next release.
* Estate-level voice settings for estate owners are not yet active. Voice for all estates is currently set to "on" and cannot be turned off. Estate-level voice management for estate owners will be available in the next release.
* Private voice channels are not always properly allocated to parcels (accessed via the "About Land" window and located under "Voice Settings"
. This will be fixed in the next release.
* More user-friendly error messages for voice are not connected to back-end error codes yet. User-friendly error messages for voice will be included in the next release.
Release Notes for Second Life 1.17.0(110) June 8, 2007
=====================================
New Features:
* Direct one-to-one voice chat is now available. This enables residents to initiate voice calls with just one other person, instead of groups. This is accessed via the Communicate button and the ChatterBox.
* Per-parcel voice settings are now available. Parcels can be set to use the same spatial voice chat channel as surrounding areas, use private per-parcel channels, or have spatial voice chat disabled.
Known Issues
* Though rare, proximal or "spatial" voice chat may not be available in all regions for which it is enabled. It works properly in most regions but there are occasional exceptions. This will be fixed in the next release.
* Estate-level voice settings for estate owners are not yet active. Voice for all estates is currently set to "on" and cannot be turned off. Estate-level voice management for estate owners will be available in the next release.
* Private voice channels are not always properly allocated to parcels (accessed via the "About Land" window and located under "Voice Settings"

* More user-friendly error messages for voice are not connected to back-end error codes yet. User-friendly error messages for voice will be included in the next release.
Now if we just have some land to buy, and the needed buying support system, to test the per parcel settings.
The above links (corrected for the Windows download) for the Voice Beta actually appeared in the not-specifically-voice Beta Test Grid page.
The Chatterbox is a sad thing. Group chat options don't get a separate tab, they appear when you click on the My Friends tab. It cuts my name off, and uses space for a volume control even though I don't have voice enabled. Sigh.