How many folks out there are promiscuous programmers? You know who you are, every project you work on, you meet a new technology or language and feel compelled to "try it out"... without giving the right amount of consideration to the language that is currently being used. Worse yet, you seem compelled to badmouth a language that has been really good to you ( I love you java;) ) and always compare the imperfections of your programming wife ( java, you're syntax is really bloated) to the sexy cool stuff from one of your programming girlfriends (ruby, I love your monkey patch).
I'm not saying that this is necessarily a bad thing, I think it is very important to have breadth in technology and learning new programming languages is a way to become a better programmer. It's more important though, to have an objective perspective about the REAL comparison and not just get infatuated with every new thing that wanders by because you think (or worse yet someone else thinks) it's better. Listen to me folks, the grass is rarely greener on the other side of the fence... It's different, and frankly it MIGHT be greener... but even if it IS greener, that doesn't necessarily make it better.
So where am I going with this? Am I suggesting that being a promiscuous programmer is a bad thing? Not really... and in that respect perhaps the metaphor is a bit bad. But, you have to suspect advice about women from a guy who's only ever been with one woman about women because ... he has a noted lack of experience. What I'm saying is when you're starting out, playing the field and figuring out what you like is important, but it's also important to commit to something and really "know" it. Make sure that changing languages is a conscious decision and you weight the benefits and drawbacks of such a switch lest you spend your entire career as a programming slut flitting between one fancy new thing and another.