ABI Research released a study last fall called "Active RFID and Wi-Fi in the RTLS Market". From the blurb:

Wi-Fi and active radio frequency identification (RFID) technologies are
locked in a long battle to capture the burgeoning market in health care
asset tracking, according to a new study from ABI Research. With less
than 5% of North American health care facilities currently equipped
with asset-management systems, this market, says industry analyst Sara
Shah, "is up for grabs."

Hospitals own lots of expensive equipment, from basic items such as
wheelchairs to the most sophisticated medical machinery. At any given
time, much of it is hard to find: either in use, or in storage. The
result: over-inventory and under-utilization of assets. Both Wi-Fi and
active RFID systems allow hospitals to know where their equipment is,
nearly in real time.

"Wi-Fi location system vendors are focusing on healthcare," says Shah,
"because most hospitals have Wi-Fi networks in place and many medical
devices are Wi-Fi-equipped for patient monitoring. The value
proposition is that they can keep their existing infrastructure and add
new elements." Wi-Fi location system vendors such as Aeroscout, Ekahau,
and PanGo will also argue that their technology is standards-based and
non-proprietary. On the other hand, RFID vendors such as RF Code and
Radianse point to the wide application of RFID for asset tracking, and
their longevity in the industry.

Wi-Fi is a viable solution for hospitals but most hospitals will need
to install extra access points because their networks weren't designed
for this purpose. "The integration process can also be more difficult
than many seem to believe," says Shah, "and requires extensive system
configuration in order to determine accurate location."

Fortunately for consultants, there is no one-size-fits-all RFID solution for hospitals. This study only focuses on one indoor positioning application, asset tracking. There are many more applications in hospitals, some with considerably different positioning requirements.

Pictured right is an AeroScout WiFi tag shot in the wild at HIMSS 2006.