With the recent (& much blogged & written about) moves by Novell & RedHat taking up postures in the Enterprise Linux market, the game now seems to be a clear two-horse race between Novell and RedHat. Novell a well-known entity in the Enterprise computing market while RedHat is probably the best known name in the Linux business
Prima facie, if RedHat does not find a big player to back up its moves (say Oracle ??? or some such player), it would find fighting with Novell (duly backed by IBM) a rather difficult task to handle. With SuSE and Ximian, Novell has enough ammunition to attack the Enterprise Server as well as the Desktop market.
How this pans out would be very interesting to observe