Current Status: You can't use data derived from restricted licence OS data with Google Maps.
There's been an on-going question about whether it is legal to display data derived from Ordnance Survey licenced mapping via google maps.
By derived data, I mean geometries which have been copied exactly from, or are composed of parts from, another dataset.
The blog post here: http://blog.ordnancesurvey.co.uk/2010/08/what-the-psma-really-means/ outlines the issue.
We've spoken to Google and they say that the OS have recently relaxed their licencing, but haven't been able to get any comment from the OS. The last post on the OS blog is from November 2012.
Does anyone have any ideas as to how the land lies here? Particularly if anyone has heard anything from the OS on this subject since November 2012.
16th April 2013: We've got an account manager at the OS now and a collegue has just spoken to him. Long story short: nothing has changed since November 2012 - any data derived from OS licenced mapping which is not specifically "free" (such as OS OpenData) may not be displayed in Google maps. Our account manager didn't know when the OS was going to come back with an answer. He said he'd chase it up.
*starts holding breath*
UPDATE: 2nd July 2013: Chasing our account manager, they reported the following (loosely quoted, do not base decisions solely on this) "The OS's position is unchanged and is not being pursued further. It is our (the data user's) responsibility to check with Google, or any other API provider, to ensure that OS rights are preserved. Rights to derived data cannot be given over to Google, as their T&C's require". Now, talking to Google, they don't think their T&C's violate the OS licence. I'm not sure this is too useful though. Our account manager has promised to send written clarification, which I will post here: a) If it ever arrives and b) if it isn't confidential. The OS blog hasn't been updated yet.
UPDATE: 2nd July 2013: Just had an email from our account manager which contradicts what we were told earlier: "...have had a chat with our lawyers who confirmed that we are in discussion with Google around the compatibility of their terms with ours. Currently, the position is that Ordnance Survey map data cannot be overlaid on top of Google Maps though we will not have an “official document/wording” available until the current discussions are concluded.". So there!
UPDATE: 6th September 2013: An email to a colleague from the boss of our account manager includes the line: "...Currently our data cannot be overlayed on top of Google Maps due to their rules around IP ownership". I don't know if this is now their official legal stance or this guy's opinion.