Blaze Lasersquirrels on Santander Cycles

Yes I thought it might be something to stop iPeds stepping out in front of a bike, because they'll see that wiggling around before the bike is upon them.

I thought that it was originally designed to warn motorists, or cars specifically, of a cyclist in the drivers blind spot. It was meant to stop cars turning left in front of cyclists. So quite a specific purpose.
Their actual usefulness in practice is to prevent pedestrians stepping out into the road when they assume it's safe because they cannot hear any cars. Or in places like the Embankment Cycle Super Highway, where pedestrians are distracted by the sight seeing or they're not even aware of the cycle path because it's no different to the footpath.
They're too dim and close to the car for drivers to notice with enough time to respond.

Was in London the other week and walking along the Green lights did alert me to a bike coming before their crappy headlights had started to light the road. So they may be OK for those bikes - but I suspect most of us have brighter lights than you get on a boris bike anyway.

And yet you felt the need to comment on the fact that it alerted you to the presence of a cyclist. How odd.

They're quite amazingly pointless, I really don't understand them.

They're utter crap.  Lest we forget, the roads are not smooth.  So never mind what shape it's projecting, it will look like a green fuzz when moving and you'll only recognise it as a bike from right on top of it...

I hadn't seen these before and I also don't see the point. I had seen something similar though for the rear that projected a bike symbol. The rear one at least had the point of protecting a sort of temporary bike lane encouraging wider over taking. The front version can't claim the same

Squirrels / nuts - I see whatcha did there...

And yes, I do think they're an unnecessary frippery.