I've seen a few people complaining about losing their signatures and that there was information that they were tracking only in their signatures.
If you are looking for what was in your signature before the forum cut over you can still get your signature from cached pages. If you update your signature frequently you may not be able to find exactly what it was before the cutover but it's better than nothing.
Do a Google search that will find a thread that you posted in. You'll see a little pull-down arrow for each search result. Hit it and choose "Cached".

That should take you to the version of the page that Google cached.
You can also use http://www.cachedpages.com/ which has a couple of caches other than Google to display. When using http://www.cachedpages.com/ you need to cut and paste in the URL that you want to see and can't just search.

