The Diffuser row is causing confusion.
Brawn, Toyota and Williams are not testing ILLEGAL cars. They have designed and run cars thay have built within their interpretation of the rules. This is clearly a valid interpretation as 3 teams, not just one, have read the rules which mean they belive there cars are perfectly legal. The other 7 teams have built cars and have interpreted the rules differently. All 10 teams will be running cars they have designed to be legal.
If the cars pass scrutenring, then they will be perfectly legal within the current rules. If a team protests it will be for a clarification of the rules, and not specifically that they belive the cars to be illegal. Basically, in simple terms, if Brawn, Williams and Toyota pass scruteninring then the other teams will be asking for the rules to be clarified as clearly if there are 2 interpretations of the rules, the rules are not clear enough.
To be honnest though, its all a bit childish. The Williams rear diffuser turned up what, 2 months ago? Im sure even the slowest developing team could have got together their own design to test in that time, but instead the complaining teams have just taken the easy route and started saying "but siiiir.... their cheating, its not fair!!". Just becasue they didnt spot the oportunity within the rules to have their diffusers like Brawn et al, they dont want anyone to.
Id love for the FIA to clarify the rules saying the Brawn et al diffusers are pefectly legal, and all the other complaining teams to go "oh, bugger, really shyould have developed a new diffuser the last few months, rather than sitting in the corner winging!"