problem with open_id_authentication_plugin and PostgreSQL 8.2

I'm using open_id_authentication_plugin (
http://svn.rubyonrails.org/rails/plugins/open_id_authentication @
7263 ) and it works perfectly with MySQL.
If I switch to PostgreSQL 8.2 (on debian lenny) with a database with
UTF8 encoding, I get the following exception:

PGError: ERROR: invalid byte sequence for encoding "UTF8": 0xe0ab03
HINT: This error can also happen if the byte sequence does not match
the encoding expected by the server, which is controlled by
"client_encoding".
: INSERT INTO open_id_authentication_associations ("handle",
"server_url", "lifetime", "assoc_type", "issued", "secret")
VALUES(E'{HMAC-SHA1}{473ec62e}{ye1zmQ==}', E'http://www.myopenid.com/
server', 1209600, E'HMAC-SHA1', 1195296303, E'��nRIʸ�lUYE��S,')

RAILS_ROOT: /home/pic/pg
Application Trace | Framework Trace | Full Trace

vendor/rails/activerecord/lib/active_record/connection_adapters/
abstract_adapter.rb:150:in `log'
vendor/rails/activerecord/lib/active_record/connection_adapters/
postgresql_adapter.rb:404:in `execute'
vendor/rails/activerecord/lib/active_record/connection_adapters/
abstract/database_statements.rb:156:in `insert_sql'
vendor/rails/activerecord/lib/active_record/connection_adapters/
abstract/database_statements.rb:44:in `insert_without_query_dirty'
vendor/rails/activerecord/lib/active_record/connection_adapters/
abstract/query_cache.rb:19:in `insert'
vendor/rails/activerecord/lib/active_record/connection_adapters/
postgresql_adapter.rb:387:in `insert'
vendor/rails/activerecord/lib/active_record/base.rb:2056:in
`create_without_callbacks'
vendor/rails/activerecord/lib/active_record/callbacks.rb:226:in
`create_without_timestamps'
vendor/rails/activerecord/lib/active_record/timestamp.rb:29:in
`create'
vendor/rails/activerecord/lib/active_record/base.rb:2022:in
`create_or_update_without_callbacks'
vendor/rails/activerecord/lib/active_record/callbacks.rb:213:in
`create_or_update'
vendor/rails/activerecord/lib/active_record/base.rb:1774:in
`save_without_validation'
vendor/rails/activerecord/lib/active_record/validations.rb:891:in
`save_without_transactions'
vendor/rails/activerecord/lib/active_record/transactions.rb:118:in
`save'
vendor/rails/activerecord/lib/active_record/connection_adapters/
abstract/database_statements.rb:66:in `transaction'
vendor/rails/activerecord/lib/active_record/transactions.rb:90:in
`transaction'
vendor/rails/activerecord/lib/active_record/transactions.rb:110:in
`transaction'
vendor/rails/activerecord/lib/active_record/transactions.rb:118:in
`save'
vendor/rails/activerecord/lib/active_record/transactions.rb:130:in
`rollback_active_record_state!'
vendor/rails/activerecord/lib/active_record/transactions.rb:118:in
`save'
vendor/rails/activerecord/lib/active_record/base.rb:470:in `create'
vendor/plugins/open_id_authentication/lib/open_id_authentication/
db_store.rb:28:in `store_association'
/home/pic/opt/ruby/gems_repository/gems/ruby-openid-1.1.4/lib/openid/
consumer.rb:681:in `associate'
/home/pic/opt/ruby/gems_repository/gems/ruby-openid-1.1.4/lib/openid/
consumer.rb:633:in `get_association'
/home/pic/opt/ruby/gems_repository/gems/ruby-openid-1.1.4/lib/openid/
consumer.rb:468:in `begin'
/home/pic/opt/ruby/gems_repository/gems/ruby-openid-1.1.4/lib/openid/
consumer.rb:301:in `begin_without_discovery'
/home/pic/opt/ruby/gems_repository/gems/ruby-openid-1.1.4/lib/openid/
consumer.rb:281:in `begin'
vendor/plugins/open_id_authentication/lib/open_id_authentication.rb:
96:in `begin_open_id_authentication'
vendor/plugins/open_id_authentication/lib/open_id_authentication.rb:
155:in `timeout_protection_from_identity_server'
vendor/plugins/open_id_authentication/lib/open_id_authentication.rb:
96:in `begin_open_id_authentication'
vendor/plugins/open_id_authentication/lib/open_id_authentication.rb:
88:in `authenticate_with_open_id'
app/controllers/sessions_controller.rb:38:in `open_id_authentication'
app/controllers/sessions_controller.rb:12:in `create'
-e:2:in `load'
-e:2

I'am running ruby 1.8.6 (2007-06-07 patchlevel 36) [i486-linux] and
edge Rails.
Any ideas?

Thanks,
Nicola