Wouldn't it make sense to hold this refresh until Lion ships? Would seem like a great machine to showcase 10.7.
I hear this line of thinking again and again.
I've been a geeky observer of Apple for two decades and I can never remember them deliberately delaying a hardware release to coincide with a software release.
They operate on their own separate tracks. If they held off hardware releases pending a new system software release, then what would they do if a late beta copy of the system software suddenly showed up a big problem ... then they'd be holding up the hardware line until that software glitch got ironed out.
Instead, they release product lines on their own schedule, and if it happens to be close to, or right in line with a major system software release, they may give you a drop-in disk, or maybe a lower upgrade price.
This whole "They will wait til Lion to release the new Macbook Air" line of thinking is dumb.