I think this is a very positive development.

First Mover

For one thing it shows Valve recognizes that although Linux may be small proportionally, it is a growing and profitable user base. (More profitable per user than Windows or Mac according to some measures.)

I expect Valve hopes to stake out first-mover status in the online game delivery arena in the Mac and Linux market. That’s good because of all the DRM schemes game publishers employ, Steam is the closest to actually being helpful to the end-user.

The Gamers

Valve bringing Half-Life 2 and Team Fortress to Linux it represents the first breaks in one  major dam where Linux falls short of Windows: games.

Many (probably the majority of) gamers have a particular mindset: they want to play the latest games.

I’m a bit of a gamer myself, and have had to adjust my mindset to enjoying the latest games that have Linux support - which means I have to be content with far far fewer titles. Especially the ”big brand” titles. 

Don’t get me wrong, those that come (Heroes of Newerth, Doom, Quake, etc.) are fantastic and perform perfectly on Linux, but the selection is much smaller.

That’s a hard sell if you’re trying to move off of Windows – how many otherwise-Linux-users do you know that keep a Windows partition or “only boot to Windows for the games”?

The remaining dams

Corporate users.

Education.

In both cases, these are “lock-in” bases for Windows. People will tend to stick to what they are taught as children (thus Microsoft’s EDGI and other such bribery programs to make sure Windows is in schools), and people prefer to use the same stuff at home and work (thus home-office licensing plans).

Still, progress is progress and Valve bringing the Steam infrastructure to Linux along with a few “AAA” titles is progress indeed.

Phoronix is reporting Proof In Steam’s Mac Client of Linux Support with this tasty tidbit they found:

#!/bin/bash

# figure out the absolute path to the script being run a bit
# non-obvious, the ${0%/*} pulls the path out of $0, cd's into the
# specified directory, then uses $PWD to figure out where that
# directory lives - and all this in a subshell, so we don't affect
# $PWD

STEAMROOT=$(cd "${0%/*}" && echo $PWD)

#determine platform
UNAME=`uname`
if [ "$UNAME" == "Darwin" ]; then
   PLATFORM=osx32
   # prepend our lib path to LD_LIBRARY_PATH
   export DYLD_LIBRARY_PATH="${STEAMROOT}"/${PLATFORM}:$DYLD_LIBRARY_PATH
elif [ "$UNAME" == "Linux" ]; then
   PLATFORM=linux32
   # prepend our lib path to LD_LIBRARY_PATH
   export LD_LIBRARY_PATH="${STEAMROOT}"/${PLATFORM}:$LD_LIBRARY_PATH
fi

if [ -z $STEAMEXE ]; then
  STEAMEXE=steam
fi

ulimit -n 2048

# and launch steam
cd "$STEAMROOT"

STATUS=42
while [ $STATUS -eq 42 ]; do
        ${DEBUGGER} "${STEAMROOT}"/${PLATFORM}/${STEAMEXE} $@
        STATUS=$?
        # are we running osx?
        if [ $STATUS -eq 42 -a ${PLATFORM} == "osx32" -a -f Info.plist ]; then
                # are we running from in a bundle?
                exec open "${STEAMROOT}"/../..
        fi
done
exit $STATUS

There are lots of  good native games for Linux, but the idea that Valve might bring over some of the big guns like Half-Life, Portal, and Team Fortress is near intoxicating for this Linux gamer!