I don't wanna wait for Thursday.
That, mind you, is when I should get
Complete Mage. It's about time the warlock finally got a bit more lovin' instead of being the red-headed stepchild of arcanist classes.
*gets off the soapbox*
I personally, however, don't see what's so unbalancing about eldritch blast being used more than once a round, at least once you reach level 20 and get into epic play. Mostly I say that because the warlock can't possibly hope to compete (especially at epic-level play) with a wizard for pure blaster archetype, let alone the Improved Spell Capacity, Multispell, Innate Spell, and other such fun things that could conceivably make a wizard a better warlock than the warlock himself.
I figure I can say that, given that I did try making an epic warlock for a campaign. At best, I was gonna do 14d6 once a round (twice if I burn a feat selection for Quicken SLA, and then only 3 times). By comparison, the wizard has more than a few spells that are at least 20d6 damage if not better -- non-epic spells, at that. That would explain why I went with an epic wizard (albeit with some swashbuckler and fighter mixed in for melee backup).
All that aside, I can't wait to see what goodies
Complete Mage has for the warlock. I know there's the Enlightened Spirit PrC meant for them, but I wanna see the new invocations, too.