Reading Goatboy's article ([URL="http://www.belloflostsouls.net/2009/08/goatboys-40k-thoughts-quick-and-dirty_23.html"]here[/URL]) really got me thinking about the role the internet can, does and should play in our hobby.
It is easy to point out the effect of instant, world wide communication has had on competitive play. Hard lists can often be described using one word cliques (Nob Bikers, Nidzilla, Lash, etc) as dominate strategies and powerful builds spread around the world instantly. If you seriously plan on being competitive, you had better keep on top of these. Imbalances certainly exist in 40k, and certain builds enable victories without the same degree of effort and chance that other builds require to achieve the game goals.
So if 40k is ONLY a competitive tournament game where it is often the player willing to spend the most money on models who wins, then the internet will definitely hasten the arms race.
However, the net can enable far more than simple net decking (as it is known in Magic: The Gathering). It can also enable more meaningful, persistent hobby play.
Wizards of the Coast's RPGA system or Privateer Press' Call to Arms League are great examples of meaningful, long term play. You get persistent rewards (treasure, veteran units, one off stratagems and bonuses, etc), there are custom scenarios and rules released monthly (or even weekly) that impact how your play and it encourages people to get involved in more friendly ways (terrain building sessions at your FLHS for example).
I'd personally love to see GW put together something like an online Planetary Empires League, where players can accrue points, earn stratagems, opt into special challenges, participate in special events and generally have something do beyond planning and painting for the next cut throat tournament rumble.
Hell, throw in a system where other players can give you points for painting, theme, fluffiness, etc.
And to top it off, make these League meaningful for players. Release limited edition models that support them. Have the results of top players impact the 40k Universe and give them attention in WD.
Of course, players don't HAVE to wait for GW to put something together.