There is a useful overview of the growing appliance market in Computer Business Review:
The appliance market is nothing if not growing, with no fewer than ten appliance vendors now identified by analyst Madan Sheina (who by the way, is one of the smarter analysts out there). Of course apart from Teradata many of these are small or very new. Teradata accounts for about USD 1 billion in total revenue (the accounts will become much clearer once they separate from NCR) though this includes services and support, not just licences. The next largest vendor is Netezza, who does not publish their revenue (though I would estimate over USD 50M). Kognitio used to be around USD 5M in revenue, though they seemed perky when I last spoke to them so may be a little bigger now. DataAllegro will certainly be smaller than Netezza, as will be the other new players. It is too early to say how well HP’s Neoview appliance will do, though clearly HP has plenty of brand and channel clout, especially now that it has acquired Knightsbridge.
Still, so many entrants to a market certainly tell you that plenty of people feel that money can be made. So far Teradata and Netezza have had the field pretty much to themselves, but the entrance of HP and the various newer vendors will create greater competition, which ultimately can only be of benefit to customers.