Welcome to the forums! I love the score chasing idea. I always really enjoy that feature in games like Shadow Complex. And to your point, it's even more relevant and exciting in pinball, where score is king (goals are fun too though; thanks for those, FarSight). Though I hate that we keep comparing to Zen, seeing something in TPA like what they do in this regard would be super.
Cross-platform leaderboards, on the other hand, are perhaps not as great an idea. I believe that there is an inherent advantage to the platforms with tactile flipper inputs and analog nudge control over the phone and tablet touchscreens. It doesn't seem fair to lump them in together. If you were playing a first-person shooter with a dual-analog stick gamepad, you wouldn't want to be matched up against someone with 1,000+ DPI mouse aiming capability. It's a moot discussion anyway, however, as many of the platform holders will never allow this.
Thanks But I still think cross-platform would work well. It's pinball, not an FPS. I don't see what kind of advantage people would have (other than hacking, if possible) since it's basically hitting flippers. The only concern would be lag, and I think that's a moot point also. Still, it would be pretty cool to have an "all-time greatest" leaderboard, even if it's not directly built into the game (ie. web-accessible).