The ME102 is the same hardware as the WAP11 anyway, in fact you can upgrade it with the WAP11 firmware to gain the extra features that the WAP11 has.

As in what features?

So does that mean an ME102 will talk to a WAP11 anyway? or does it need to be flashed with WAP11 firmware? can I use a ME102 as an AP client to other Linksys gear

Yes, the ME102 can act as a Wireless client and connect to any 802.11b AP including Linksys. It doesn't need to be flashed with the Linksys firmware to achive this, and i'm not even sure that would be a good idea.