From the Apache::DBI docs:
Apache::DBI version 0.90_02 and later might work under mod_perl 2.0. See the Changes file for more information. Beware that it has only been tested very lightly.
And Changes says
0.93 January 10, 2004
- Change $r->connection->user to $r->user to make AuthDBI work
with mod_perl 2.0 (thanks to Neil MacGregor and Brian McCauley )
0.90_02 January 10, 2003
- Changes to make Apache::DBI load and function under mod_perl
2.0. A few important notes: connect_on_init does not work yet
and there's no automatic RollBack cleanup handler when
autocommit is turned off.
So, it seems like Apache::DBI will (and probably already does) support mod_perl 2 as well.