Clearwire (s CLWR) is launching its Clear WiMAX service in Las Vegas on July 21. That’s great news for conventioneers (especially the numerous tech-focused shows in the area every year) and casino attendees, never mind the locals, who will get to play with the new 4G technology. Day passes are available for $10, with mobile plans starting at $30 for 2GB of usage, and $40 for unlimited use at home or on the go. Clear claims it provides download speeds of up to 4Mbps and upload up to 500Kbps. But how will the network hold up when the gadget-heavy Consumer Electronics Show comes to town next January?