For those with custom domain names... $20/year vs $60/year for Google Apps. Ads or not, thats a compelling savings for my many pet projects where I only need 1 or 2 @projectname.com mailboxes.
It's a shame that Google Apps got rid of the free tier. I've started 2 businesses on the free tier (< 10 accounts) and now pay around $200/month for each company as they have grown.
Now Microsoft will gain some ground in the email arena.