I stumbled across this today while working on a mac doing some photo editing. Archaeologist working at the Pompei site are using iPads in the field. Not strictly linked to collections, but its interesting to see how they are using them.
The team are using a paperless approach, where all data is collected using off the shelf apps on Ipads, like iDraw and Omnigraffle rather than taking hand notes and then carrying out data entry. The information is then transferred to on-site server which then links to the project database. The project director believes that using iPads has saved a year of data entry.