Asked for in this thread...
Attached is a script to batch convert a directory of images (you pick the type - jpg, png, gif, bmp) to gimp patterns. The default save location is the user pattern directory (on xp it is c:\Documents and Settings\<User>\.gimp2.x\patterns\). You can specify a prefix for the pattern names so they will be grouped together in the pattern menu. They get named <prefix>-filename_without_the_extension.
Unzip and save the script in your script directory, then refresh scripts, or restart gimp.
In gimp 2.4 it should end up under the toolbox menu "Xtns->Batch Convert to Patterns...". With Gimp 2.6 it seems to end up under "Filters->Batch Convert to Patterns..."