This represents a conundrum for voters, especially those who would prefer to support Palin but have a few other options (like Bachmann). It also offers some confusion to pollsters, who must decide whether or not to include Palin as an option. There is no consensus. You can see thise confusion reflected in the recent round-up of national polls and from the current early primary polls (which are being updated much more frequently now). Some pollsters are including Palin, and others aren't. Additionally, some pollsters are releasing multiple sets of polls, with Palin and without.
In nearly every case where Palin is included, Bachmann is now leading her. But once again, these results are influenced by the fact that voters prefer to support candidates whom they believe are actually running. Palin may not have said she isn't running, but she hasn't taken any steps that indicate she will run.
For the time being, Elephant Watcher is including Palin in the "potentially running" category, rather than the "declined to run" category. Why? Because Palin, while not in the race, still exerts some influence. Bachmann may lead Palin in the polls, but Palin still gets a fair amount of support in them. Were Palin to step aside officially, Bachmann (and Cain) might get a boost in support.
On the other hand, Palin is under no obligation to say that she isn't running. The speculation keeps Palin in the public eye, which she prefers, so it's likely she will not officially declare herself out of the race until the last moment.
Consequently, Elephant Watcher will place her in the "declined to run" category under the following conditions:
(1) Palin states that she will not run, or
(2) Palin does not enter the race by some point in September, after which it is too late to run.