Hi Ian,
I have never tried this combination but I don't think that this will work. The 1200 Series AP's are designed to work with Cisco Pre-standard PoE not IEEE-802.3af as supplied by the 3com. Have a look;
Most Cisco Aironet access points use inline PoE from power injectors or Cisco powered EtherSwitches (Cisco pre-standard PoE), but the Cisco Aironet 350, 1100, and 1200 series access points do not directly support IEEE 802.3af power sources. These access points were designed before the IEEE 802.3af power standard was ratified and must use third party products such as PowerDsine to support IEEE 802.3af power sources.
From this good doc;
Cisco Aironet 1200 Series
Cisco Aironet Power Over Ethernet Application Note
http://www.cisco.com/en/US/products/hw/wireless/ps430/prod_technical_reference09186a008039e541.html#wp39318
Here is the 3Com PoE info;
In-line Power over Ethernet Switch with 24 10/100 Ports
The SuperStack 3 Switch 4400 PWR combines Power over Ethernet technology (IEEE-802.3af) with the advanced features, simplicity, and style of the SuperStack 3 Switch 4400 family.
From this 3Com doc;
http://www.3com.com/products/en_US/detail.jsp?tab=features&pathtype=purchase&sku=3C17205-US
**I would probably go ahead and order the - AIR-PWRINJ3 for each AP. They are really quite cheap 🙂
Hope this helps!
Rob
