Taylor Swift is poised to make her "Saturday Night Live" debut. The teen singer-songwriter will be the musical guest on this weekend's show. She recently noted on her MySpace blog that she was thrilled to be performing on the NBC show, especially because it's happening on her mom's birthday. She wrote, quote, "I don't think either of us would've believed you if you would've told us a few years ago that we'd get to spend her birthday in New York City -- at 'Saturday Night Live!'" Hosting "SNL" tomorrow will be "How I Met Your Mother" star Neil Patrick Harris. GET A SNEAK PEEK BELOW!