Well on the iMac I think you can have both a bluetooth keyboard and a bluetooth mouse connected at the same time which is probably true for other devices as well. --- MacBook Pro with Retina Display | 15.4" 2880x1800 | Core i7-3615QM @ 2.3GHz | 8GB DDR3 1600MHz | GT 650M 1GB GDDR5 | 256GB SSD | OSX 10.9 | Windows 8 Pro
"In a Bluetooth piconet one master can communicate up to 7 active slaves, there can be some other up to 248 devices which are in sleep mode (may participate to communication actively when another active device goes into sleep mode)."
Go to Google and search "How many devices can be connected to a Bluetooth adapter?" --- 3570K (4.8 GHz) | Dual-X 7970 | ASRock Z77 OC Formula | Corsair Vengeance 2x 4 GB | WD Black 1 TB | Corsair TX750 | XSPC Raystorm 750 RS240 Kit | NZXT Phantom