Rupert Candy wrote:

They've started piling at the southern end of Blackfriars railway bridge (by the old bridge supports) - presumably
for the second river crossing

Not exactly. It's being used for structural inspections between June 23
and December: http://www.pla.co.uk/notice2mariners...lag/2/id/3053/

On the subject of Blackfriars, I believe the building on the SE corner
of New Bridge and Queen Victoria Streets will be demolished from next month.

and there are hoardings at Farringdon by the north end footbridge, though no signs of actual construction
yet.

Judging by how long it's taken for the hoardings to go up, it'll be
interesting to see if the new bridge will be ready in time. Network Rail
seem confident though.

I also noticed a stripy eye-catching "Thameslink Project" information stand at Moorgate - currently empty, but presumably will
soon hold "You're not getting any Thameslink trains any more" leaflets...

Close enough. If thameslinkprogramme.co.uk is anything to go by, it'll
be more like 'Take a deep breath. We can't stop at Barbican and Moorgate
any more'

You can also add the Herne Hill siding and Luton Airport Parkway/Mill
Hill Broadway platform extensions to your list...