Pukka, a favorite tool of the Delicious crowd, has added support for Ma.gnolia with its 1.5 release.
Thanks to Ma.gnolia’s Mirrord API (which mirrors the Delicious API), a number of formerly Delicious-only applications can also be used with Ma.gnolia. Pukka now ranks among them, though not with out a few discrepancies, notably no support for spaces in tags or ratings, but these are minor issues that can be worked out over time (note, to enable private bookmarks, check this out).
What’s interesting about apps adding cross-domain API support is the slow emergence of standards in new areas (i.e. outside the standard protocols). A framework for application developers that handles multiple bookmarking APIs that essentially do the same thing would be of great value, similar to the work that Jacob Jay started with his MediaSock framework (for publishing to over a dozen media services). I could see such a framework being really useful in browsers, feed readers, media players and similar applications.
Anyone?
Factory Joe 
Just as I was upgrading Pukka, this post came through Google Reader! Gotta love the interwebs.
Standardized API formats need to become more common. The discrepancies between APIs will lead to a lot of programming that could be easily avoided simply by swapping a URL (in my opinion – and I’m a designer, not a programmer). Ma.gnolia has the right idea, I’d love to see this become more commonplace.
The trouble with ‘API mirroring’ is that the API of the service that gets mirrored was probably designed exclusively to support its own functionality and therefore was not designed in an abstract way suitable for adoption by varied other services. Sure it’s great that services are embracing common interoperability, but where’s it going…
Also I hate to harp on (probably said it before 😉 but common APIs are useless without simple endpoint URLs that users can enter easily–or a discovery mechanism as in the MediaSock Service API (not to be confused with the Client Framework which abstracts the different service providers)…
I think it would be great if sites could have an endpoint URL similar to how proxy servers offer a single URL from which to gain all of the configuration settings for clients. I’ve found that with Pukka, sure, I let the API URL be changed, but I also now have a bookmarks URL to open your bookmarks (which differs between del.icio.us and Ma.gnolia), a registration URL, etc. Having those be available from one place would be really useful.