I do exactly what you're asking. I work for a pharmacy chain and our heavy lifting is done with Spring MVC but I use Play! to write smaller internal applications all the time. One of the greatest things about play is when my boss comes to me about needing a new app I have it up and off the ground in an hour.
One application I did allows our pharmacists to double check cash prescription prices by bouncing the drug and quantity off our central databases. Another one sets up an interface where our quality control people can enter SQL queries, save them, schedule them to run, and then have the results emailed to them. They use this to find various statistical outliers.
We also have a fairly complex social network written in Spring MVC that I will be porting to Play! throughout 2011. The network is for our pharmacists and pharmacy techs to collaborate about prescription compounding and whatever else they want to talk about.
Finally, I'm in the process of finishing up a B-to-B app between a large third party prescription buying group and our pharmacy chain. I can't go into detail about it because the contracts are not finalized but it will be nationwide and pretty high load. The scheduling was very aggressive and without Play! it wouldn't have been possible. See that's the best thing about Play!, even if you outgrow it you can prototype and get something live very fast.
