Suddenly my number of available Gmail invitations has leapt from the usual half-dozen or so to 50.  Google are deluding themselves if they think I have that many friends!  If anyone would like an invitation, drop me a note or leave a comment with your email address (and I'll delete it afterwards to fend off those evil spam harvesters).

Presumably this implies that Google are planning to dramatically ramp up the user base, so it can't be long before the system is open to all.