strange locks

HI,

I am running PostgreSQL 8.0.x with a database that does not have foreign
keys. However, sometimes the following messages appear:

deadlock detected: Process 10029 waits for ShareLock on transaction
65272; blocked by process 32436.Process 32436 waits for ShareLock on
transaction 65117; blocked by process 10029.

I also see (right after executing a ps) that there are lots of messages
"select waiting".

1 - Does it mean that process 10029 owns transaction 65117 and process
32436 owns transaction 65272 as a transaction acquires an exclusive lock
in its transaction id ?

2 - How is this situation possible ?

3 - What could cause the status ("select waiting") ?

Best regards, Alfranio