The recent interest on fictions and the imagination in science is very encouraging - fictionalists are no longer dismissed as "irrationalists", "relativists" or, worse, "postmodernists". There is however a serious argument that fictionalism is incompatible with scientific realism. It goes roughly as follows. i) The hallmark of a fictional assumption (eg. regarding frictionless planes, point particles, or the elastic solid ether) is the irrelevance of its truth-value to its function in inquiry. So ii) if fictions are indispensible to scientific modeling, then science does not aim at truth - not through its models at any rate. Thus iii) fictionalism - the claim that fictions are rife in science since indispensible in modeling - is inconsistent with scientific realism.
Maybe one should not care about scientific realism, but I suspect this argument is nonetheless fallacious, and I gave a preliminary reply in the introduction to the book I edited for Routledge. There I argued that realists can happily accept a weak form of fictionalism, which endorses what I call fictive representation -- i.e. controllably false idealisation of the properties of real entities. So frictionless planes are ok, point particles may be, but the ether definitely is not. I'm now working on a paper where I claim that even this is too conservative, and that if the right account of fictions is provided then the realist can safely go all the way to the strongest form of fictionalism above. (There is of course a long story behind what I take to be the right account of fictions). The problem lies with the middle conditional premise (ii), but there are few worked out arguments on this topic, which makes it hard to tell what would be standard and what not, so I'd be interested in whatever intuitions people might have (if they have any!).