The official Windows Phone 8.1 GDR1 update changelog has mention of one new change. While everyone has liked the ability to delete and forward multiple messages, seems one can also delete multiple calls and contacts post Windows Phone 8.1 update 1. Though deleting contacts needs to be supported by the manufacturer.
To delete multiple calls (or groups of calls) at one time, tap More > Select calls, select the calls or groups of calls you want to delete, tap Delete, and then tap Delete to confirm. (To delete multiple calls or multiple groups of calls at one time, you need to have Windows Phone 8.1 Update installed.
Want to delete multiple contacts? In People, tap More > Select contacts, select the contacts you want to delete, tap Delete, and then tap Delete to confirm. (To select and delete multiple contacts, your phone manufacturer needs to have set up your phone to do this and you need to have Windows Phone 8.1 Update installed.