Jaiku they basically strangled by making invite only. Gmail got big by promising large mailboxes where the users would never really need to delete a mail.

Docs is fighting what amounts to a RAD these days, and is to much for the casual user (notepad), to little for heavy users.

Maps however is doing ok on the mashups front.

I wonder however if they have a interesting thing going with dialcentral, at least if they go global, like skype...