firstrowidiots.com

I just thought it was another lame MLS attempt to go Euro along the lines of absurd team names ("real" salt lake?)  There are a few open air stadia in europe with the word "arena" attatched to it; AOL arena in Hamburg comes to mind.  Even though it has a retractable roof, Amsterdam ArenA is another one (usually stadiums with such roofs would still be called stadium or park here in the US)

After having looking it up, it turns out that -- esp. in Germany -- open air stadiums with the word arena as part of the name are usually those with corporate sponsored names, so I guess Red Bull Arena would have made sense in this tradition.  I also guess that they realised that American fans would have just been confused about naming an outdoor stadium an "arena", especially with its association with basketball and hockey facilities.

Finally, as a side note, arena comes from the latin word for sand, which was useful as the primary surface when gladiators battled wild animals or each other, to absorb the blood.  I wonder if blood will be spilled on the pitch from disgruntled Metrostars fans about this whole Red Bull debacle...