Foursquare for BlackBerry has just updated to v1.9.97 and has an exciting new feature. You can now link your Foursquare account to your American Express card for more rewards! Simply link the accounts, check in on Foursquare at participating merchants and tap "load to card" in the special, then pay with your AmEx card. On your next AmEx statement, you'll see the credits applied from the specials. 

From the Foursquare blog:

Last March, we rolled out a small test with American Express: link your AmEx and foursquare accounts, spend at least $5 at a local merchant in Austin, and get a $5 savings applied directly to your monthly statement. When we launched, the response was overwhelmingly positive. So, after SxSW, we sat down with American Express to plot the future.

Today, we’re happy to announce that the partnership is going national. Across the whole country, at select merchants, you can now check-in with foursquare, pay with your American Express card, and get big savings on your monthly statement.
More businesses are going to be joining soon, and we’ll share those as they go live. Redeeming these Specials is a totally effortless experience. If you’re a cardmember, link your accounts now to start saving!

They are kicking off the new features with specials at H&M (Spend $75, get $10 back) and Sport Authority (Spend $50, get $20 back) nationwide, as well as some restaurants in New York. This service is effortless to use as you don't have to clip coupons or even show your phone to a cashier; credits are automatic. Full details can be found on the Foursquare blog, including instructions on linking your American Express card to your Foursquare account. 

Full details and instructions on the Foursquare blog
To download Foursquare for BlackBerry v1.9.97