After thinking it through...
...and asking a bit of advice, I decided to share this.
First the two replies to the message on the OpenBSD mailing list:
This tells us who discovered it (Ben Gras of VUSec) and what they named it (TLBleed).
A Google search for VUSec and four mouse clicks leads to this:
After reading a bit I disabled hyperthreading from the BIOS on my systems. I think that until I know more the folks at OpenBSD are right and it's better to play it safe. I am writing this because I think that security by obscurity is no security at all.