In a nut shell, not yet. Your question depends on what happens from here on out. The foreclosure process in California can about 120 days. If you go through that process and your home is foreclosed on you should be protected from capital gains taxes under the Mortgage Forgiveness Debt Relief Act of 2007. This is only the case if your home is your primary residence (no second or vacation properties). There are several other qualifications you must meet under the Act to have your debt forgiven. If can provide you with all the requirements if you like, or you can look it up online. Since I do not know you nor the specific facts involved you should contact your accountant, tax attorney, or you can call one of the free helplines. HopeNow is the best in my point of view. Their number is (888)995-HOPE.
You should know that you may have other options to foreclosure. Many lenders STILL won't talk to people who are not yet in default. I recommend being very persistent with your lender...in other words, KEEP CALLING. Make sure to write down ALL conversations and dates and keep track. Ask to speak with their loss mitigation department.
To learn about other options that may be available to you, you can read my E-Book, which provides a lot of insight and other remedies that may be helpful to you. It can be purchased at http://www.MortgageWalkawayOptionss.com.
The bottom line is: don't give up on working out a modification with your lender. There are programs out there that may be able to assist you. Call HopeNow for starters. Let me know if you have any other questions and best of luck to you.