The question of whether men can be feminists comes up from time to time in the feminist blogosphere. I like Majikthise's take on it the best. Of course, men can be feminists! Actually, I insist that the men in my life be feminists, and I take great pleasure in informing certain men that they are in fact feminists even if they have never thought of themselves as such.
Feminism should not be considered an exclusive ideology, but a basic position held by all enlightened people of common sense. I see it as a great big tent. There is no purpose in categorizing certain people as lesser feminists because they happen to have been born male. If you truly consider women's freedom, equality of opportunity, and dignity to be CRUCIAL priorities, then you are a feminist.
I have found, however, that a lot of men may believe in women's freedom, equality, and dignity, but fall down on the portion of the definition that calls for these to be "crucial" priorities. Classic example are progressive Dems, often male, who believe that we shouldn't protest the nomination of anti-Roe judges because overturning Roe will motivate a groundswell of public support for more progressive candidates. This is an anti-feminist position because it proposes sacrificing women's rights for the greater good of progressive politics. Another example might be the Mark Starr kind of feminist who believes in feminist goals as long as women behave in a particular way. But women can take these anti-feminist positions as well. While women are more likely to be feminists than men, I see no reason to define feminism as including only women.
There is perhaps good reason to be more skeptical of men who claim to be feminists. For obvious reasons, men will generally be less acutely aware of the inequities in society that affect women. Men are perhaps more likely to adopt the "feminist" label for self-serving reasons, perhaps to ingratiate themselves with certain women, for example. And there are plenty of anecdotal tales or examples of men who claim to be feminists or allies of feminists but then turn around and use the most tired anti-female stereotypes around, like this guy's statement in his comments thread about the "shrill humorlessness" of feminists.
But my philosophy is to take men's claims to feminism at face value until there is probable cause to believe otherwise. Ultimately, this is a discussion about semantics. We are talking about words, and I see no cost to being as inclusive as possible.