Seems like I'm on a Google Calendar sync roll this morning, so I might as well talk about GooSync as well. GooSync allows over-the-air sync of your Google Calendar with your mobile phone provided your mobile phone provides SyncML support (there are a lot of phones with this support and the GooSync site provides downloads for certain phone operating systems like Windows Mobile that require a SyncML client install). This is a 2-way sync, so information entered into your phone calendar will be sync'd back to your Google Calendar.
GooSync offers a free option and a premium option for around $38 per year -- full feature comparison here. Regardless of the plan that you choose, both the free and premium plans are listed as having support for Google Domain, which makes me assume that this would work for Google Apps Premier, but if anyone can verify that, it would be awesome.
The GooSync FAQ states that they are working on a Google Contact sync service, which would be pretty awesome as well. Imagine using either the Gmail Mobile Java app or Gmail forwarding for e-mail along with GooSync for calendar and contacts -- that would be pretty powerful Blackberry comeptition at a very low implementation cost.