I read somewhere last night that Toyota may actually want to sell their entry, not simply give it away. That may be the reason for FIA wanting to clarify Toyota’s legal position:

Press Release
Toyota And Bridgestone
04/11/2009
The announcements this week by Toyota and Bridgestone of their withdrawal from Formula One are of concern to the FIA.

Bridgestone has given almost 18 months’ notice of its intentions, thereby allowing the necessary arrangements to be made for the future supply of tyres to the championship.

Toyota’s decision, however, comes just weeks after its F1 team signed the new Concorde Agreement until 2012.

Urgent clarification is now being sought from the Toyota F1 team as to its legal position in relation to the championship. This will have a direct bearing on the admission of any future 13th entry.

The FIA has repeatedly warned that motor sport cannot outpace the world economic crisis. That is why the competing teams have been asked to cut costs and the entry of independent teams has been encouraged.

The FIA accepted the cost-reduction measures put forward by the teams on the basis that they would ensure a long-term commitment to the championship. Toyota’s announcement demonstrates the importance of the original cost-reduction measures set out by the FIA.

The FIA will now work to ensure that Toyota’s departure is managed in the best interests of the championship and will continue to encourage the F1 teams to undertake the necessary cost-cutting measures for the good of the sport.

Toyota’s loss simply means that the new Sauber gets a place on the grid and one less engine supplier (although I don’t think any of the private teams were using Toyota Engines for 2010).  Renault pulling the plug drops the team count to 13 with yet another engine supplier gone.