As impatient people craving access to Google Voice continue to wait for the arrival of that joyous invitation email, Google Voice head Craig Walker gives us a brief insight into just how long of a wait some users may be looking at. A short while ago, Walker tweeted that the team is currently working on invitations that have been pending since the days of GrandCentral before it moves on to more recent invitations requested since Google acquired the service. The clarify that time frame, Google snatched up GrandCentral way back in July of 2007 — meaning that if you’ve requested an invite recently, you’ve probably got a hell of a wait ahead of you considering the GrandCentral invite system was killed two years ago.