It's one of the biggest L.A. real estate deals ever. The NY investment firm Blackstone Group is selling 23 Socal properties to Maguire Properties, including the 52-story Two California Plaza downtown. Maguire is already downtown L.A.'s biggest landlord (it owns the 72-story U.S. Bank Tower and the 42-story One California Plaza), but the Blackstone deal also includes a bunch of OC properties (Tower 17 in Irvine and Stadium Towers Plaza in Anaheim). The sale appears to be a further debt-reducing effort by Blackstone after its $39 billion buyout of Equity Office Properties Trust, a Chicago real estate investment trust. Blackstone has been selling off other blocks of property. What all this means for office tenants is the likelihood that rents will be going up. Socal's office market has been on fire over the last year or so, thanks to low vacancy rates and little new construction. Bloomberg News appears to have broken the story on Saturday; LAT has additional info this morning. Nothing has been formally announced.