SETI@home "classic" will end then the separate BOINC-gui is finished, and their servers can take the load.
Not sure on the server-situation, except AFAIK there haven't been any crashes or anything in November, and atleast with current load no problem keeping up with demand.
For windows, the standalone-gui is more or less complete, but still some small problems in v4.55.
Also, the screensaver in v4.55 isn't working if running as service, but AFAIK this is already added so should be included in next alpha-release.
The biggest change in v4.55 is the new installer, that among other things installs BOINC as service on NT.
This new installer is MSI package, so can costumize installation and deploy to many computers.
Since win9x doesn't have service-installation, the solution here is AFAIK still not finalized.
As for non-windows, there's still no gui reached alpha.