This is kinda interesting. The folk at Google Groups have built in a dynamic email masking system as part of their service. The protection takes the same format as the email masks people have been using for years, techniques such as writing “at” instead of “@” in the address or inserting the string [NOSPAM] and so on.
Google has decided to visually suggest an antispam measure by inserting “…” in the published email address and then linking the string to a kaptcha interface (see above).
I like the idea, I’m not 100% convinced this isn’t a little confusing for the novice user but I guess time will tell. Still, I love the idea of starting an interface from an element the user has created in the first place.