Germany isn't a part of the UK, so things will work exactly as before. There's an existing mail service in Germany called G-mail, and the agreement (after a court case in 2007) is that the owner of that trademark can use it in Germany, Monaco, Norway and Switzerland, but nowhere else.

The English trademark was owned by someone else, and wasn't in active use, afaict.

Update: http://techcrunch.com/2010/05/03/gmail-uk/ says Google reached a settlement after "engaging in legal proceedings at the trademark office" (read: pointing out that it wasn't in use, in order to get it revoked).

Nothing, this applies only to UK users for the moment.