I managed to get Spreadsheets on the day it was released. But, before I did, Google told me they would send an invitation via e-mail to let me know when I could receive the service.

I just didn't get one. I don't think it's down to Gmail's spam box, either. I checked 'em.

I've also just received my invitation to Web Albums, which actually was in an email, to my surprise (http://picasaweb.google.com/joecritch)

Everyone's accounts who registered today should be starting to come through.

This also brings something to mind: do Google take into account how much you use their beta services? Or is it definately just "first come, first served" – perhaps a bit of bias?