FYI,
I’ve just updated the license on GNU Radio from GPL version 2 or later
to GPL version 3 or later.
The text of GPL version 3 is here:
The GNU General Public License v3.0 - GNU Project - Free Software Foundation
The updated FAQ is here:
Frequently Asked Questions about the GNU Licenses - GNU Project - Free Software Foundation
Compatibility between various GNU licenses is discussed here:
Frequently Asked Questions about the GNU Licenses - GNU Project - Free Software Foundation
Eric