Larry mentioned a list of Google services that are shutting down, but one he did not mention that is also being let go by Google is Jaiku. From what I understand Google will release the Jaiku code under the open source Apache license, so that somebody else can take it where they want to. I think Nokia should pick it up and carry it since it is highly focused on S60 users and would fit perfectly into their focus on providing services.
There is no good S60 Twitter client and Nokia could take the Jaiku code and probably add in Twitter support, like we get with Mauku on the Nokia Internet Tablet. We would then have finally have an awesome Twitter/Jaiku client on Nokia devices.
If you are not familiar with Jaiku, it is a social networking/microblogging service similar to Twitter. However, it is actually a bit more like FriendFeed since you can comment on posts and see an entire conversations around someone's post. I preferred using Jaiku over Twitter because there is a great S60 mobile client I was able to use on the go. I significantly decreased my usage the last few months as I was bouncing around other mobile operating systems and there is only a S60 Jaiku mobile client.
At this time we do not know what will happen with existing user accounts or the service since there is no organization that has yet said they would continue the service. I encourage you to write to people you know at Nokia and encourage them to pick it up.