Hiya, found this on a french forum:
Skype sur votre Blackberry : Les applications - Forum Blackberry
the app is called: "IMO beta" here:
https://imo.im/blackberry
EDIT: wait just saw that it's compatible from OS 5.0 +, no idea about 7.0, how ever the OP on the french board said he put it on his Torch meaning works at least on OS6.
Also found the original source from crackberry:
http://crackberry.com/imo-announces-...y.com+Blogs%29