ActiveSync supports syncing over networks, including WiFi networks. Just make sure that option is enabled on the host PC under Connection Settings. One warning, ActiveSync 4.0 will no longer support network syncing *sigh*. Seems they decided it was more secure that way. But the current version, 3.8 does and there's no need to upgrade to 4.0 when it comes out unless you're using a Windows Mobile 5 device (none have been released yet).
-------------------- Lisa Gade Editor in Chief, MobileTechReview