Update #3: A $499 limit has been added to qualify for free processing.
Update #2: It’s back to being free again through 03/12!
Update, 03/08: It appears that GroupMe has gone back on their word and has started charging for this service early. They have edited the page and deleted the info on the service being free through 03/12. Congrats to those who got in before they made the change!
Split by GroupMe is a way for friends to chip in for something together and pay back one person for laying out the funds to buy something. There will be a 4% processing fee starting on 03/13/13, but until then you can send credit card payments to anyone for free.
Considering that this is intended for small purchases I’d imagine they may block large transactions.
If you try out the service please post how it works out for you.