Might I add: when there is an announcement that there will be a cash offer, or whatever the deal is and the date of record is given in the future the stock price will generally rise to a few pennies below that cash amount, or, as WZ pointed out, over the amount.
At this point in time, when the stock price matches the offered price, is when you need to review your tax situation. This is when you can sell if you would be better off claiming capital gains on your taxes, or if you would rather have the money than the shares/dividends deal that might be offered. It's important to find out what your best option is regarding the taxes so that you can take action before you are locked into the deal. You might have to sell for a couple of pennies less, but you might make more in tax savings.