Lightweight APs have a default limit of 12 clients per AP, but this can be changed. Cisco recommends no more than 25 clients per AP, but it can easily handle more. How many more simply depends on your conditions.
Keep a few things in mind:
1. Your actual data rate is generally a little less than half your advertised rate (22Mbps on a 54Mbps link, for example)
2. You're sharing the ACTUAL data rate with every other client on the AP. So if 20 users are sharing a 54Mbps connection, they'll all get barely over 1Mbps
3. Any slow clients, 802.11b or otherwise, take more time to communicate with the AP and thus slow all other clients down
4. RF space is a shared medium, and congestion avoidance mechanisms in 802.11 start creating a LOT of overhead as you increase client count significantly. This starts dropping your actual data rate, so you might start getting only ~15Mbps on a 54Mbps connection.
All that said, I doubt you'll start seeing disconnects until you hit client numbers in the 30s. But again, take all the above into consideration as you evaluate your environment, your application delay tolerance, and your bandwidth requirements per user.
Jeff
