Generally there is a delay from when a new version is released to the TAC site then posted to our cloud servers. The period is not fixed but tends to be 2 - 3 months. I don't have an exact date for 4.1 to the cloud but it is coming very soon.
*** UPDATE ***
4.1 is now available for download from within Central. Go to Maintenance then for the upgrade method select "Manual" then choose v.4.1.0.0 from the drop-down list. Automatic should be available in a few days.