Obviously the Fast track review will come into force (maybe) on Aug 1st (there is a move from house of Lords to block the review but dont think it will happen), the whole of the Feed in Tariff system is under comprehensive review which will be concluded by the end of the year with the review to take effect Apr '12.
My feeling is that Sub 4kw will get cut 5-10%, over 4kw cut 30%, 150kw 3-5%, 250 and above unchanged.
Now for the bad news the FiT scheme has a finite amount of funding which when its used its gone, there will be no more within this spending review period which takes us up to 2014-15. The total amount of funding equates to if I can remember rightly somewhere between 400-500Mw currently as of a couple of weeks ago there was 145Mw installed so far. My best guess is that with the massive amount of free solar schemes that are currently running ( I know of 3 that are doing between 10,000 and 30,000 and there lots more in the pipeline) the money will be all spent by the mid to end of next year.
So make the most of it now!