Hi! Nice to meet you! I'm a newbie too, hoping to run the Princess Half in 2012
I'm using an iPhone 4, which is multi-tasking enabled and has built-in GPS. I have two apps that I use when I run,
Nike+ and
C25K (there are several versions - I use the one that says "Powered by RunHelper"), and this setup has been working really nicely for me!
I use Nike+ for overall "big picture" progress tracking, and C25K is the training program I'm using to get started. I turn on the Nike+ program first, click the start button and then turn on C25K and click the start button on that one. It works best if you keep C25K in the foreground and play your music through C25K. It's really neat because the male voice in C25K chimes in with the "walk", "run" and "cooldown" prompts and the female voice in Nike+ chimes in every five minutes with progress info - duration, distance and pace. At the end of the run, I just let the music continue to play through C25K if I want to extend my run or cooldown - C25K stops measuring, but Nike+ keeps tracking. And when I arrive back at my apartment, I switch over to Nike+ and finish the run there. At this point, I'll usually get a motivational message (like congratulations from Lance Armstrong on beating a personal best) and the data automatically loads up to my Nike+ account online. I love logging in to my Nike+ account online after each run to see my overall progress, an animation of my route, progress toward my goals and seeing where I stand in challenges that I've joined. It's so fun and motivating!
I have found the GPS-based distance and pace information in Nike+ to be surprisingly accurate - not so much in C25K - so Nike+ for overall progress tracking and C25K for walk/run prompts. Awesome combo!