A new post outlines why Gore hasn't endorsed yet
There you have it. I think Gore's profile has risen enough since 2004 he will have more of a positive effect. I'm also skeptical of the idea that Gore would "jinx" Obama but it's funny that Gore thinks about the Gore jinx too.
1.) The memory of the ill-fated Dean endorsement looms large for him.
2.) (Which is somewhat related to 1.) He's worried about somehow jinxing Obama.
3.) He's enjoying the contrast between himself (statesman-like, above the fray) and Bill Clinton, who's been rooting around in the mud for his wife and damaging his legacy in the process.