Changing names is a very political and long-process at Google. Google, being Google, decided to go with the German spelling, "kaffein." A German chemist, Friedrich Ferdinand Runge, came up with this in 1819. So due to the issues with naming it "Caffeine," Google decided to put the breaks on that and use a less known word for it, kaffein.
Now that Google Kaffein has been renamed, Google has now taken it live.
Webmasters at WebmasterWorld seem to confirm the launch of kaffein. We have dozens of reports that it is now live, the reports starting coming in last night.
This does not appear to be an April Fools joke!
Forum discussion at WebmasterWorld.