CONCAT strings from multiple rows in one SELECT

[Develop01]

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 |
+-----------------------+