The current version of Signal is 1.34.2, the newest release is 1.35.1.

Updates since then:

1.34.3:
The help menu is a little more helpful. Quickly report bugs in more languages, or use the new shortcut to join the Signal Desktop beta and help us find them even earlier. Thanks, @82ba10b5e8dc!

1.34.4:
This update fixes a few rare bugs that the Signal community discovered during the beta testing process. If you would like to test new Signal features before your friends (and sometimes discover new problems in the process), the Desktop beta program just might be exactly what you've been looking for. Simply launch Signal and select "Join the beta" from the "Help" menu to turn the dream into a reality. Thanks in advance!

1.34.5:
We added system theme support across all platforms. It's always darkest before the dawn -- especially if you configure your appearance settings based on sunrise and sunset.

1.35.1:

• Start using your mouse's scroll wheel as a rotary dial with support for one-to-one voice and video conversations on Signal Desktop.
• Accept the unexpected: Message requests let you quickly see more info before accepting the request, deleting it, or blocking the conversation.
• Give peace a chance and temporarily mute notifications for any conversation.

With the big update being voice and video-calls on desktop.

Release:
https://github.com/signalapp/Signal-Desktop/releases/tag/v1.35.1

.zip of source:
https://github.com/signalapp/Signal-Desktop/archive/v1.35.1.zip