Google have been making it harder to sign up to their free version of Google Apps recently, and they have finally pulled the plug on it and will no longer be accepting applications for the free accounts.
This does not affect existing users.
For new clients wishing to have a similar service the free options we are currently experimenting with are:
Zoho – Free for upto 3 users, 5GB mail storage per user
Microsoft Live for Domains – The new Outlook email service offers unlimited storage, access to Office and Office 365. We are currently testing to see how many users can be set up with this. While the domain management isn’t as elegant as Google mail, and it does not integrate with phones apps as well as Gmail, it does offer upto 500 accounts per domain which should be more than enough for any client.