Mariana and others,
        A survey called "Current Issues in University Museums 1986" by
David Huntley, Lyndel King and Tom Toperzer addressed your question.
In the summary of 119 responses, the results were:

To whom does the museum/gallery director report?
        Enrollment 1,000-5,000
                President 42.4%
                Vice Pres./Provost 27.3%
                Dean 9.1%
                Dept. Head 18.2%
        Enrollment 5,001-15,000
                President 7.2%
                VP/Provost 21.4%
                Dean 35.7%
                Dept. Head 23.8%
                Other 11.9%
        Enrollment 15,001-25,000
                Pres. 20.0%
                VP/Provost 25.0%
                Dean 45.0%
                Dept. Head 20.0%
        Enrollment 25,001+
                Pres. 8.3%
                VP/provost 20.8%
                Dean 37.5%
                Dept. Head 16.7%
                Other 16.7%

It also says 56.8% said the museum was a "separate department" and 43%
"part of a department".  (I don't have the original questions, but it
sounds like "department" here may also have been taken to apply to a
division or school.)

David Huntley conducted a similar survey under ACUMG auspices in 1991 but
has not been able to publish the results.  A summary report that may have
only gone to ACUMG board members indicates that "it appears that the
larger the collection and the longer the institution  has been in
existence, the more likely it is that the director reports to central
administrative level (either a Vice-President or President.)"  Of 107
respondents, the level reporting to was:
        Pres. 11.2%
        Acad. VP/Provost 25.2%
        Dean 25.2%
        Chair 16.8%
        Other 21.5%

My personal experience at Saint Mary's College has been that as the
college has grown, I have reported to the President, then to a Special
Assistant to the President, then the Academic Vice President and now the
Dean for Academic Resources, formerly the Library Director until she got
this extra responsibility.  (I notice 4 other museums of the 107 in the
1991 survey also indicated reporting to the library head.  In a survey of
"small liberal arts colleges" reported in The Journal of Academic
Librarianship, July 1994, 10 out of 54 respondents "stated that the
library of their institution was responsible for managing the art
collection either alone [6] or in cooperation with another administrative
unit [4].

So . . . as your MUSEUM-L survey will also probably show, there are many
models.  The conventional widsom is that because the museum serves the
campus as a whole, not just one department, it should have a fairly centralized
position
position.  But its success seems to depend a lot more on having a strong
advocate (or several if possible) with influence on the people in the top
levels of authority than on its exact position in the organizational chart.

Well, guess this is a little long for an e-mail message, but I hope it
will be helpful.

Incidentally, now that I have the attention of the university museum
folks, is it true that non-New Englanders can subscribe to ACUMGN-L?  I
sent a subscribe message but I don't think anything has come in.