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presently operating b - factories ( pep - ii and kekb ) have exceeded their design goals , both in peak and integrated luminosity .
pep - ii @xcite , running from mid-1999 to april 2008 , has reached 4 times the design peak luminosity , delivering to the babar experiment an integrated luminosity larger than 557 fb@xmath1 ( see fig .
[ fig1 ] , left plot ) .
kekb @xcite also started operation in 1999 and reached a peak luminosity 60@xmath2 higher than the design value , delivering about 820 fb@xmath1 ( up to april 2008 ) to belle ( see fig .
[ fig1 ] , right plot ) . in table
[ t1 ] the performances reached at the end of april 2008 are summarized .
very good performances and high operation reliability represent a big success for all the factories , and upgrade of an order of magnitude or more in luminosity is desirable for investigation on particle physics beyond the standard model .
.b - factories performances ( april 2008 ) . [ cols="<,^,^",options="header " , ]     [ t2 ]      superb has very ambitious goals in terms of peak and integrated luminosity , supported by a new collision scheme and confirmed by beam - beam simulations .
the initial design meets the goals requested by the experimenters .
the test on this scheme is in progress at da@xmath3ne and encouraging results have been achieved at the moment .
the work on the accelerator is continuing to focus on possible issues .
the next step will be to form a team to complete a technical design report by 2010 .
operation of present b - factories has been very successful and an upgrade of is desirable and feasible .
kekb and pep - ii experience was highly positive and instructive , but going to higher luminosities is much more challenging : the  brute force " approach seems hard to pursue and new ideas need to be tested .
solutions to problems can come from the collaboration between international laboratories , as it is done for the ilc .
two different approaches are being considered for super - kekb and superb , with different challenges .
super - kekb is the natural continuation of kekb , studies are advanced and it is waiting for funding .
superb exploits new concepts in colliding beams physics , allowing for the collection of a larger data sample .
the test of the novel collision scheme is in progress and the first results of the upgraded da@xmath3ne are very encouraging and important for the very high luminosity regime required by future flavour physics studies .
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pep - ii at 1.2x10@xmath4 @xmath5 s@xmath1 luminosity " , proc . of particle accelerators
conference , albuquerque , june 2007 .
k. oide et al ,  compensation of the crossing angle with crab cavities at kekb " , proc . of particle accelerators
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p. raimondi , d. shatilov , m. zobov ,  beam - beam issues for colliding schemes with large piwinski angle and crab waist " ,
lnf-07/003 ( ir ) , january 2007 .
 superb conceptual design report " , infn / ae-07/2 , slacr-856 , lal 07 - 15 , march 2007 .
 super - kekb letter of intent ( loi ) " , kek report 04 - 4 , 2004 .
s. bettoni , e. paoloni , p. raimondi ,  design of the qd0 for superb ir " , icfa workshop on e@xmath6e@xmath7 factories , april 2008 , novosibirsk ( russia ) .
operation of the b - factories ( pep - ii and kekb ) has been very successful , both having exceeded their design peak and integrated luminosity and provided a huge amount of good data to the experiments . 
 proposal for upgrades , in order to achieve about two order of magnitude larger luminosity , are in progress in japan , with super - kekb , and in europe , with superb . 
 very high beam intensity , very short bunch length and low interaction point @xmath0-functions are the key points of the japanese design , very challenging for the hardware components ( rf , vacuum ) . on the other hand superb exploits a new collision scheme , namely large piwinski angle and  crab waist " , which will allow for reaching a luminosity two order of magnitude larger without increasing beam currents and decreasing bunch lengths . in this talk the present status of the two projects will be briefly reviewed .