With the "New Ning" your profiles are now visible to anyone who has a ning account. To help cut down on spam sent to you, you need to do the following....
On all networks you belong to either set your profile to "Members" or "Just Me", this can be done by clicking settings then privacy.
Next and very important... go to www.ning.com, and set your profile to "Just Me", do this the same way as above...this will/should according to ning, stop others from seeing your profile.