[spacehome]

I'm not sure of the details, but I think it's rooted in tax law -- that the options are classified differently if they're exercised within a year of their creation.

[cbr]

If that's the issue the options could vest monthly but just prohibit you from exercising them for a year.

(not a lawyer)

The standard reason for the cliff is that at first an employee slows everyone else down as they come up to speed, and then they start to help.