Umm, an hour of downtime doesn't mean your data is gone. I'll also echo earlier comments -- locally hosted email generally has more problems, as no company but the largest enterprise has the same magnitude of IT equipment and experience as Google.
I've never really understood why so many Slashdotters have this attitude about hosted services. Perhaps they are local IT folks for smaller companies, and fear for their jobs?
It's more than that. There are more moving and breakable parts between you and a hosted provider than between you and an internal service, which changes the math a bit.
Some of the single points of failure are shared between both approaches too, so they're a wash for a small implementation. If you're a small company and your non-redundant core switch fails, your email is down either way, because you can't get to your email server or to your hosted provider, no matter how redundant your provider is. There are various components for which this is true, which helps to mitigate the benefit of a hosted service where your mail server is replaced by a massively redundant cluster.
You also have additional dependencies. If you're a small business with a single T1 to the internet, let's say, and the telecom bunker outside your building catches fire and you lose internet access, you've got problems. With a local email service, internal mail works, but you can't send email to or receive email from external users (let's pretend you don't have an offsite secondary MX or an outbound mail spool where this stuff queues, mostly invisibly to users). For organizations that are hugely dependent on internal email, that's quite a bit better than having no access to your (hosted) email at all.
Additionally, you get concerns about "If we outsource this today and we have problems in 2 years, will we still have somebody here who can design/build/find a better solution, or will it cost us a fortune in consultants if we let the in-house expertise lapse?".
You also have support issues. Google specifically is well-known for only doing things that can be automated (and doing them well, mind you). Support isn't always one of those things, and small companies are well-acquainted with getting the shaft from vendors because your business isn't worth enough for them to care (check out the quality differences between the enterprise and SMB versions of various products for examples). Given the importance of email to most organizations today, folks are a bit reluctant to hand it over to an outsider with minimal financial incentive to devote resources to their specific problems.
If you're a 5-person business, outsourcing email is likely a good idea, but once you start getting into the teens and twenties or so, it's probably worth a look at your particular circumstances before continuing that assumption.
Full disclosure: I'm currently a local IT guy for a smaller company, with enough on my to-do list that if I thought outsourcing email would work well for my users and save us time & money, I'd be all over it.