You can bet Microsoft won't support Linux any time soon. I'm still waiting for their Silverlight WMV codecs so I can these in Moonlight. They're supposed to license these commercially for Linux users, but in the meanwhile Silverlight is already being adopted.

For remote computing you can use Rdesktop, VNC (over ssh -C), or NX (or ssh -X). If you set up SSH keys you can easily run an X application remotely using ssh -fXTC hostname application_name and ofcourse you can use SSH to run CLI applications.

E.g. PHP applications with Apache or Lighttpd are also an option.

If you want to use Web 2.0/SaaS there are other alternatives like Google Gears or use a commercial alternative with a SLA.

If you want to keep your data synced you can use SyncEvolution/SyncML, rsync (grsync).