CONCAT strings from multiple rows in one SELECT

[Broccoli2]

I'd like to be able to return a single cell containing a string formed from all the records in a table, ie

mysql> SELECT OrganisationName FROM t1;
+------------------+
| OrganisationName |
+------------------+
| this             |
| that             |
| the other        |
+------------------+

I want this:

+-----------------------+
| SomeSelectFunction    |
+-----------------------+
| this, that, the other |
+-----------------------+

At the moment the best I can do is use a variable, but this takes the same number of rows to build up:

mysql> SELECT @um:=concat_ws(", ", @um,t1.OrganisationName) FROM t1;
+-----------------------------------------------+
| @um:=concat_ws(", ", @um,t1.OrganisationName) |
+-----------------------------------------------+
| this                                          |
| this, that                                    |
| this, that, the other                         |
+-----------------------------------------------+

Is there a way to return that final value in one SELECT? I tried adding a LENGTH(@um) and ORDER BY but it didn't work. I'd rather not use two SELECTS since I'd like to build this as an Access SQL Pass Through (although I know a workaround to execute multiple SELECTS in one query, I'd rather not use it as it's a bit messy)

Please help!

-Rob