Well, this is the first I've heard about this:

We have been involved in a dispute regarding the Gmail trademark in the UK. Another company has claimed rights to the Gmail name. We have tried to resolve this dispute through negotiations, but our efforts have failed.

We are still working with the courts and trademark office to protect our ability to use the Gmail name, but in the meantime, we want you to have an email address you can rely on.

The Gmail Team is dedicated to offering the best email service to our users. Our email service stays the same no matter what the logo is or what follows the @ symbol. This change lets our team focus their time on continuing to bring you excellent service.

Apparently, the company Independent International Investment Research had been using the GMail name for its online services 2 years before Google’s GMail launch.

The GMail trademark has also hit troubles in Germany, where they were forced to change to Googlemail a few months ago. It’s a terrible shame, really, as one of the things that I like about GMail is nice short snappy addresses you can get out of it. cappsy@gmail.com is mine, for example. cappsy@googlemail.com just doesn’t sound or look as good.

Obviously Google would rather not this was case, but at least they’re giving it a go to try and sort it out. So, what about us UK users who are currently using an @gmail.com address? Will we be forced to change?

Unfortunately, we don’t know. We would love to say that your address will always remain the same. But the trademark issue is still unsettled, and unfortunately, we cannot predict what the other party or the courts might do here. You can always use your same username with an @googlemail.com address to avoid this issue later on. But trust that we will do the best we can to make sure your email address won’t ever have to change.

For now, our plan is only to issue @googlemail.com addresses to new users. Trust that we will do the best we can to offer all our users a reliable and consistent email experience.

More information over at BBC News, if you’re interested.