Office 2008 for the Mac is a huge release for Microsoft, and a big deal for most Mac users. I've been anxiously waiting for the newest version of Office for one thing only: Entourage 2008. For my money Entourage is the best mail client on OS X (feel free to call me names in the comments), but Entourage 2004 certainly shows its age.
Entourage 2008 looks great, but not all is sunshine and daisies. Entourage 2008 stores most everything it uses in one big database file. There are many reasons to do this, but are also a few drawbacks. One of the biggest Leopard related drawbacks is the fact that Time Machine does file level, not bit level, backups. Every time a file is changed it is included in Time Machine's backups. Every time Entourage gets an email, you add a contact or event, or label something Entourage's database file is changed. Add to this the propensity for that database file to grow rather large and you can see the problem here. Microsoft suggests you simply exclude Entourage's DB from Time Machine's backups, but I hope they come up with a better solution in the near future.