A Lobber storage-node consists of a BT client and a control plane that talks to the lobber service. This model could work for a mobile client too but the BT client may need to be stripped down to support fewer features. BT is well adapted to a mobile usage pattern where the device changes network connectivity often a situation that BT can handle quite well. .
The control plane (PUSH+ATOM/RSS) should not present a problem for a mobile device but certain mobile devices have access to native notification services that could work even better (eg iphone iPhone notifications). The size of each notification message is very small (a torrent infohashinfo-hash) which does should not present a problem for any notification technology.