Whilst trying to find out how to contact the Google Accounts team [*] I stumbled across their online contact form here:

http://www.google.com/support/accounts/bin/request.py

If you select "Other" and click "Continue" you'll end up here:

http://www.google.com/support/accounts/bin/request.py?hl=en&ctx=accounts_hc&contact_type=other&Other_product=&submit=Continue

One of the options in that list for "Your Google Account issue" is:

   I received a notice that Gmail service was added to my account.

They could easily do this to people who signed up for Google Talk using a non-Gmail address as they've already picked a nickname/username – and this already appears as usernamegmail.com in Gmail / GTalk. They could also do this for Picasa Web Albums users and Google Page Creator users, although they'd need to know which username to use as you can create multiple ones.

So, are Google actually doing this?

[*] http://blogoscoped.com/forum/77806.html#id77815

Isn't there a "Convert google account to gmail account" button somewhere?

I think Gmail-free-for-everyone is close. (Who knows? 5GB Gmail available to everyone from January 1st 2007?)