> When has Google shut down a paid service that was popular and under heavy development like GCE and GAE?

As far as I know, never. I've been compiling a list of live and shut down services/products/etc (~299 so far), and while payment doesn't seem to be an important factor (plenty of shut down paid things, including many more advertising services than I expected), I cannot name a service which was under heavy development and was shut down during said development. However, I think that is just because development tends to stop before the final death knell. Reader, for example, used to regularly update and improve during its heyday.

It has to do with margins and focus. Companies time and time again sell /shut down profitable divisions, simply because they're not performing "good enough," whatever that may mean. Google essentially has no competition in advertising so anything else is a joke compared to that. Who knows?

It doesn't have to be as dramatic as a complete shutdown. I bought into Google Apps for Business on the implicit promise it could one day completely replace desktop office apps.

All serious development has slowed down to a crawl. New developments are mostly cosmetic. Bugs never get fixed. Microsoft, miles behind not so long ago is now streets ahead with Office 365, and Google has quite clearly stopped giving a crap.

Google has never shown any interest in the long term pursuit of any product or service that couldn't be sufficiently exploited for advertising, directly or indirectly (collecting data to sell to advertisers), paid or unpaid.

They don't have to shut it down. They can raise price dramatically, like the Map API price hike, to drive people off. The thing is we don't know whether the current price is viable for Google or not, or whether it will stay viable tomorrow. It's just there are too many of these instances that people have lost trust. Once trust is lost, it's very difficult to earn it back.

I suppose it wasn't very popular, or under heavy development, but I used Google Translate, and also was impacted when AppEngine went through the crazy price hikes.

Google Answers is the only service I can think off. I don't think it was popular though.

AppEngine was a pay service too but price rise pretty much forced many people out.