OK, I admit, I've had a drink of the platform-as-a-service Kool-Aid. And I liked it. I think the concept of an on-demand development platform is pretty kickin' and I was, I must say, duly impressed by Marc Andreessen's Q&A with Marc Benioff at Salesforce.com's Tour de Force event here in San Francisco.

Neophyte that I am.

I went to Ning, Andreessen's latest love child, to check out all the networks people have developed (during his Q&A Andreessen said there are about 150,000 individual networks created on Ning, which, like Salesforce's Force.com, is an on-demand development platform).

Here's the message I received when I clicked on Ning's "All Networks" tab:

"Ning is taking a short break!
Our experienced technicians (pictured) are currently hard at work so as to bring Ning back online shortly. Thanks for your patience. If you have any questions, feel free to visit the Ning Blog."

The picture? A (cute) stuffed monkey tapping away on a keyboard, eyeballs glued to a large monitor.

A couple years ago Salesforce had some up-time problems, though those seemed to have calmed down since. But Ning's message brings about a good question: What exactly are the challenges to computing, or coding, in the cloud?

And I think it's just one of those questions that only time will answer.