The plugin is compatible with WordPress MU installations when enabled on a per site basis.
If a single Price Tapestry installation is to be accessed from multiple blog instances then identical settings can be used. After configuring the plugin as required for the first time use the export settings featured to create a custom pto_default.php file. Thereafter, simply enabling the PriceTapestry.org plugin in additional installations will automatically import your custom settings.
If each blog instance is required to access its own Price Tapestry database then each instance can always be configured manually as required. However, when WordPress MU is enabled, the place-holder %MU_ID% (blog instance site ID) is available and may be used in any of the following PriceTapestry.org Settings:
Base HREF
Install Path
$config_databaseTablePrefix
For example, consider the following sub-domain setup using WordPress Multisite:
http://foo.example.com/ (site id 2)
http://bar.example.com/ (site id 3)
...required to access the following Price Tapestry installations respectively:
http://www.example.com/pt_2/
http://www.example.com/pt_3/
(where each Price Tapestry installation is using a $config_databaseTablePrefix value of "pt_[Site ID]_")
This could be achieved using the following wp-admin > Settings > PriceTapestry.org values:
Base HREF
http://www.example.com/pt_%MU_ID%/Install Path
/home/example/public_html/pt_%MU_ID%/$config_databaseTablePrefix
pt_%MU_ID%_