Dave Winer likes to talk about how bad the battery life is on MacBooks. He's always looking for a power outlet.
Maybe if Dave's OPML.app was a Universal binary and wasn't generally a CPU hog, his battery would last longer. OPML is built for PowerPC only, therefore it has to be emulated by Rosetta, and therefore using more energy than it would if it was native.
See for yourself. Download his OPML Editor, and launch it. Also launch Activity Monitor so you can watch OPML's CPU usage. Do some simple stuff in OPML like Cmd-N to open a new outline. Watch the CPU usage...
OPML's ancestor, Frontier, was written back in the day of cooperative multitasking on the classic MacOS. Yes it was multithreaded but it was never very good at yielding the CPU. Any app that sucks CPU time on a laptop (Mac, Windows, Linux or otherwise) is going to drain the battery.
This isn't the MacBook's problem.
Update: Rosyna corrects me on Rosetta - it's a dynamic binary translator, not an emulator. Thanks! So it doesn't have as much runtime overhead as an emulator (over time). As she says, "A CPU hog is a CPU hog." Gotcha.