Following hot on the heals of Gmail going offline, I'm now seeing the offline option for Google Calendar (at least in my google apps account). I set it up on my home computer earlier but didn't have a chance to find out how far in the future/past it stores offline.

Here's the support doc for it: http://www.google.com/support/calendar/bin/static.py?page=offline_faq.html&hl=en

Yes it's new :)

now official:http://googleenterprise.blogspot.com/2009/02/offline-also-available-in-google.html

yep yep, its new... here are my screenshots... now if they can get this feature quickly on regular Gmail > Calendar please =)

http://lh4.ggpht.com/_P_0ThwxH4IE/SY6I5Ut0NRI/AAAAAAAAAMk/SPBUpAtpYPU/s800/Google%20App%20-%20Calendar%20Offline.png

http://lh6.ggpht.com/_P_0ThwxH4IE/SY6I5TjKTpI/AAAAAAAAAMs/nwokD2gceRE/s800/Google%20App%20-%20Calendar%20offline%20%28settings%29.png