Slashdot has this note suggesting that the UK Internet Service Provider, Sky, is having trouble migrating its users to Google Apps. Reading through the commentary, however, it seems like the real problem stems from poor user documentation, and not technology, per se:
Rupert Murdoch-owned British ISP Sky is migrating their customers to the Google Apps platform, and the customer experience is terrible. Their 1 million customers were told that they need to change their client settings to enable SMTP Authentication and other settings on a certain date ? but not to do it before then or their e-mail would break; but if you don't do it on the date your e-mail will also break. Oh, and if you're a POP user you also need to enable that manually in the 'Skoogle' interface, as seemingly they chose not to run a system-wide command to allow it for all users. In addition, if you want help then you're pretty much on your own.
Bad? Yes. But could much of it have been alleviated by better documentation/a cleaner transition guide? Probably. The fault seems to be less with Google than with Sky.