Like Spamfire 1.x, Spamfire 2.0 lets you create Rule Filters that check incoming messages for certain criteria. The interface for creating and editing Rule Filters is slightly different, but the basic settings are the same.
The main difference in version 2.0 is the way Rule Filters are used to make a decision about incoming email. In version 1.x, you could assign a score to a Rule Filter. In version 2.0, the Rule Filters do not have a score; they now work like the Sender Filters (the Friends & Spammers List). They simply mark a message as good or as spam, without any of the "fuzzy logic" of the score system of the old Rule Filters. They override the spam score and cause a message to be treated as spam or not-spam, regardless of what the other filters decided.
In version 2, you can create Rule filters that use regular expressions.
See Rule Filters in version 2.
More about Spam Scores in 2.0.