I hope it's just temporary. Otherwise...

Although I dont see the Last.fm.option / settings anywhere in the app, my scobbling does seem to work with latest app and firmware... 

(and yes Last.fm is very important to me) 

Exactly the same as you. Scrobbling still works, but I am wary that they will at some point allow themselves to remove that. I will be reassured when Last.fm will appear again in the services list.

Yes, hopefully Sonos understands this is a very important feature for users!

There is a discussion on the Last.fm forum, but it seems that no one at Last.fm wants to respond or reassure us. Don't hesitate to post new messages to show that we exist and that the Last.fm team puts pressure on Sonos so that the service is restored.

Last.fm service not anymore accessible in Sonos - Get Help / Apps and Scrobbling - Last.fm Support Community

I added my reply there as well :)

There are also some threads on Reddit: 
https://www.reddit.com/r/sonos/comments/1cnul0h/recent_sonos_app_update_has_removed_the_lastfm/

There is an official answer from Last.fm about that here :

https://support.last.fm/t/last-fm-service-not-anymore-accessible-in-sonos/93376/4

Things are simple : Last.fm offered help to Sonos to implement the service, something that wouldn't be complicated. They are still waiting for an answer from Sonos.

SO IF SOMEONE OF SONOS IS READING THIS : DO SOMETHING TO FIX THE ACCESS TO LAST.FM SERVICE. AND ASK HELP FROM LAST.FM THEY ARE READY TO HELP YOU! AND THE LEAST OF THE COURTESIES IS TO ANSWERING AND GIVING US AN APPROXIMATE DATE OF THE FIX.

It’s not scribbling to Last FM for me, any longer; and I am deeply disappointed. The connection to Last FM meant a great deal to me. 

O wow, that would be crazy!
For me it was still working yesterday, but also have concerns as the service isn't selectable anymore in the app.

Hopefully this gets restored soon!

It is scrobbling… there was just the notorious delay when using Spotify. But I am scrobbling from Bandcamp now, and am delighted.

Mine is still scrobbling ok after today's update.

I have been scrobbling since the update, though I more recently discovered it wasn’t listed under my connected services in the app. However, I did download the Desktop app and it is visible there. Obviously if it’s still scrobbling for some, the credentials and “connected service” are still available on Sonos’ servers.

Ah, good one to check on the Desktop app!
I suspected there is more stored in the Sonos system then we see in the new app, otherwise Sonos wouldn't be able to scrobble at all :P

Any update on this from Sonos? Is last.fm ever coming back?  My system is still scrobbling but I have no access to the settings.  

Same here, it would be very nice to hear confirmation of longterm Last.fm support.

Sonos support told me today I was crazy because my system still had last fm. Like everyone else iOS app wasn't showing. 
 

scrobbling stopped 7/21 so that's around noticing it was gone. 
 

I checked the desktop app and it was there. I couldn't re auth my account I had to remove last fm from desktop and readd it. 
 

after that scrobbling came back (no help from sonos aside from hinting last fm was still linked ‘somehow’).