IBM Put a few figures on slides at LotusSphere.
I'm just repeating them here for easy reference.
Number of Notes/Domino 7 Seats: 12 Million
Number of ND7 Downloads: 11,575
Number of Notes Users: 125 Million
Number of Competitive Migrations: 1300
Bowstreet (December 2005)
Bowstreet provide portal development tools.
PureEdge Solutions Inc (July 2005)
PureEdge are open standards forms developers.