Please come back after following this link to a great post by Matt Aslett of the 451 Group.
I think a major consideration for a healthy open source project in 2009 that will make it at the enterprise level is just how well the core developers of any given open source initiative embrace the entrance of well-organized professional service (PS) companies to deploy said solutions. There's a bit of a love-hate thing going on there, since the founders and their core devotees of any initiative have poured a great deal of sweat into the solution they've reared, and they deserve to reap the benefits of their work. The PS companies are normally not constructed to give back to the initiatives in as robust a manner as the project originators, which adds to the tension.
As long as the PS companies bear this in mind when entering the game, they can contribute back with funding, sales and marketing support, and development contributions wherever possible. The added benefit all around is increasing the legitimacy of the open source project, since with any successful software application community there are professional services firms built specifically to implement these kinds of solutions at the enterprise level.