Here is something I have not seen mentioned on any blogs yet that I noticed while reading through the Lotusphere PDF’s.
In the Lotus Notes 8.5 client there will be support for iCal Subscriptions and Federation. While it is only mentioned on a single page in the PDF (INV106) the screenshot looks quite interesting. It looks like you can turn on and off calendars just like in Apple OS X’s iCal application. The different calendars can be assigned different colors and I believe that you can ‘subscribe’ to an iCal file on the web and receive updates from it.
This is an interesting feature that I’ll be keeping as eye out for more details on.