There are questions over how apps might scale to some of the devices, which are larger than a cell phone, Google’s mobile product development director Hugo Barra told paidContent:UK during a briefing with journalists in London on Thursday.

“It could be any number of things - form factor, the limited number of pixels, does it have a GPS on it?

“We’re concerned that users will get a good experience at the end of the day.

“You can have Android Market if it leads to a good implementation. We have to make sure that every device meets the criteria for a good experience for Android Market.”

In one way, this appears a different approach from Apple (NSDQ: AAPL), which makes unreversioned iPhone applications available to iPad via iTunes Store and simply scales them up for iPad’s larger screen.

In another way, Google laying down markers which tablet makers must meet to hit Android standards is little different from in the phone area - but it seemed significant that Barra was clearly cautioning about this when it comes to tablets.

A wave of iPad-alike tablets is coming from original equipment manufacturers, poewred by Android, the most high-profile of which so far is Samsung’s Galaxy Tab.
Google’s spokesperson said she would not comment about Android Market on the that device - but the market is present on it.

Right now, Google is also investing more in to Android mobile development than Android as a desktop or laptop OS, Barra added.

Giving latest stats, Barra said there are now 80,000 apps on Android Market, and 180,000 developers.

It’s still not clear when Android Market reform, including introducing Google Checkout billing to more countries, will happen.

A new version of Google Maps, with walking directions, and Street View, with easy relocating of pegman, were due to be unveiled for Android on Thursday.

Update: Google tells us…

“We are doing a number of things to ensure that the user experience with applications on Android devices is great.

“For example, we have created a Compatibility Test Suite for handset manufacturers. This tests devices on a range of factors to ensure they are compatible with the Android platform. Only devices that pass this test will be allowed access to Android Market.

“Today, there are more than 60 compatible devices in the hands of consumers.”