Citrix is the best way to this, they have tied in tightly to the Mac - even the ipad and iphone.
http://community.citrix.com/display/xa/Citrix+Receiver+for+iPadThis a pretty cool video showing how they allow you to use your iphone as a mouse track pad for the ipad! Crazy!
http://community.citrix.com/display/ocb/2010/04/09/Citrix+Receiver+for+iPad+-+Demo+1+-+Wireless+TrackPad