Most of what needs to be said about the hole California has dug for itself can be found at Calitics. I have two brief additions.
The first is that in terms of gross state product the $26B dollar deficit is quite manageable. Using 2007 numbers, it amounts to 1.45% of GSP. That works out to about $716 per person. My guestimate of how many people could afford to cough up extra money is 20%, so the bite would be a more significant $3600 per person for the more narrow group. But if half of the deficit is closed by cutting spending, only 10% of the population would have to cough up extra dough. The main point is that the crisis is essentially political, not financial.
The second is that a constitution shouldn't contain policies. The text should be limited to rights and procedures. Requiring certain levels of education spending or limiting how much taxes can increase just should not be included. (The one policy added to the federal constitution - Prohibition - was an abject failure.) California's initiative process has allowed voters to put inflexible policies into the constitution without consideration of the effects on current or future budgets. This needs to be changed. While there is the danger that bad current policies will once again be included, I think California has no choice but to call a constitutional convention. The state is clearly ungovernable.Update: Compare and contrast.