A spokesman for Nvidia Inc., which makes the MacBook's 9400M graphic chip that controls the screen, one of the biggest energy users inside any notebook, deferred all questions to Apple.
Isidor Buchmann, president of battery equipment vendor Cadex Electronics Inc., and blogger at BatteryUniversity.com, said he thinks that Windows could be at fault.
"Think of how long it takes for Windows to boot," Buchmann said. "I compare it to the original Ford Model T, which took five minutes for you to crankstart in the morning."
Microsoft declined to comment, only saying by e-mail, "This isn't a support scenario for Microsoft (Apple is not a licensed Windows OEM) so we have no information to share."
A VMware spokeswoman noted that a June update to Fusion 2.0 "lowered overall CPU usage, which lowers overhead and helps improve battery life for all operating systems."
OpenOSX claims that battery life under its virtualization software is actually pretty good. That, says OpenOSX owner Jeshua Lacock, is due to the WinTel software being able to take advantage of the MacBook's power management features.
Will Windows 7 fare better?
According to Microsoft, Windows 7 has been re-engineered to have faster boot times and drain 11 percent less power than Vista.
But without new drivers from Apple or updated support from virtualization vendors, Windows 7's battery life may be as poor or worse than its predecessors.
When new drivers or support will arrive is unclear. Apple hasn't said when it will release Windows 7 drivers for Boot Camp.
VMware also declined to say when it would release new Windows 7 drivers, and otherwise officially support, the OS, which is due in late October.
"We haven't done specific testing with regards to battery life and Windows 7 at this time," the WMware spokeswoman said.
That could mean many more months or years of poor battery life for Windows 7 users on MacBooks.