fatal error - different CATALOG_VERSION_NO

i just cvs update and recompiled -current. upon starting up i get:

<cut>
# su pgsql
$ pg_ctl start -w -D /var/pgsql/data&
$ Waiting for postmaster to start up...FATAL 2:  database was initialized
with CATALOG_VERSION_NO
 200012280,
        but the backend was compiled with CATALOG_VERSION_NO 200101061.
        looks like you need to initdb.
...............................
</cut>


do i have to follow the upgrade procedures? i have some important data
that i don't want to lose or mess up on.