Are Wildcard Certificates Supported by Mobile devices?
Wildcard certificates are not support by mobile devices, or Windows Mobile, until Windows Mobile version 6.
The browser used in these types of devices is a cut down version of the desktop versions, and support for wildcard SSL certificate was removed prior to version 6.
The only option, if using Windows Mobile version prior to 6, is to purchase certificates with a fully qualified domain name for the domains that require mobile device access.
Microsoft information on certificates included with Windows Mobile 5.0 and Windows Mobile 6