[macamac]

Thins server should be updated so people who updated can play.

[Prodigy9]

This is largely dependent on updates to Bukkit. In general, it's best to avoid updating until a few days after the new content is released if you play lots of SMP.

[eah]

Thins server should be updated so people who updated can play.

You can always downgrade, that is if you kept a copy of the 1.1 jar. Or you can always try getting the 1.1 jar from someone else, which can be considered pirating. Next time, copy your jar, then upgrade.