Apple is being told to appear in court as part of an ongoing investigation of Google by the Federal Trade Commission. The FTC wants details on how Google became the default search engine for the iPhone and the iPad. Those default settings are getting a lot of scrutiny as Google is investigated for unfairly dominating the market.

There are two main concerns here. One, whether Google favors its own products in search results over its competitors. So, for instance, you search on the name of a restaurant and you get a Google Places review of it before you get a Yelp review, even though Yelp is a much more popular service. Second, whether Google is charging more for ads by its competitors. For instance, does Microsoft pay more for an ad than Minnesota Public Radio would because Microsoft makes Bing and MPR does not?

These are not new issues. They’ve led to a lot of complaints in Europe especially, but the subpoenaing of Apple is a sign the heat is getting turned up here in an FTC investigation that’s been going on for over a year.

And if the feds come down hard on Google for this, it could really shake up all sorts of parts of the web.

Microsoft, in particular, is sitting in the bleachers watching this and waving a pennant that says “Go FTC!”