Right before finishing the quest Eureka! I fast traveled out of the Hoover Dam and back to The Strip, to prevent the ending of the game - just like I did on Fallout 3 with Project Purity. I of course first completed the quest for the Achievment, and in disappointment watched the inevitable ending cut scene and credits, then reloaded the save right before where I had finishing it, and fast traveled out of the location. I then continued to do several quests, leaving Eureka! alone. After doing some quests, and gaining several levels (leaving me at 29)I went gambling in the strip. After leaving a casino it now says I am 'currently unable to fast travel from this location'. No matter where I walk to or what I do, it always says it. I cannot fast travel. I have a save before I started Eureka! but it's quite a few lower levels now... and I was almost at 30.
Damn you Fallout.
Loading my save I did right before initiating Eureka! fixed the problem. Damn, I have to do four hours of stuff again. Oh well.
Ha. New Vegas just froze while writing this.