Aviation Week magazine [p-35; Oct/11/04] explains that
the unwanted roll of SSI at Mach 2.7 on Sept/29 was the
result of a "high-Mach snap"; a condition not unknown to
aerospace engineers.

i.e. Many high-speed craft at high-Mach numbers
in the past have lost directional stability, especially at
low or negative angles of attack with tragic results.
Obviously, Rutan, has overcome this problem with his SS1
craft in the hands of Brian Binnie on Oct/04.

But...How does one deal with/prevent the "roll problem" on future [2007?]
'tourist' spaceflights?
My guess is is that 'vernier thrusters', diagonal to the spacecraft's longitudinal-axis, possibly using hydrogen-peroxide, may be added
to Virgin Galactic spacecraft when they are built, to counteract
any such unwelcome roll-tendancies.

BTW...If you want to go up on a suborbital flight onboard a Virgin
Galactic, but don't have the money, or don't want to mortgage your house,
7-UP softdrink corporation is offering a "free ticket" to a lucky contest
winner.
Yes, Robert! This is SPAM...but it's space-related.

cheers.

Jacob