Over the past few years I have fallen in love with graphs made with R. They can be as beautiful as your imagination can make them. When converted to .pdf, thanks to vector graphics, they stay crisp at any size.
Unfortunately, it is not always easy to preserve this beauty when I want to publish these graphs or show them in professional presentations. Yes, all the glories of R graphics are preserved perfectly using knitr + Latex + Beamer + Slidify. However, I have many presentations that I have painstakingly prepared in PowerPoint. If I want to add just one new image to such a presentation, it would be very difficult to remake the whole presentation in a different format. Furthermore, almost no Psychology journals accept Latex documents.
Because I was unaware of a better solution, I have made graphics in R, converted them to .pdf, used Adobe Reader’s snapshot tool to copy the images (zoomed to 200%), and pasted the images as bitmaps in PowerPoint or Word. The images look okay but they are not truly scalable. It has been disappointing to see them lose image quality.
MS Office documents have a scalable vector format for images called enhanced metafile (.emf). R has the ability to save graphics as enhanced metafiles but the results are ugly (no anti-aliasing).
The best (free) solution I have found so far is to save graphics made in R as scalable vector graphics (.svg), open them in Inkscape (a free alternative to Adobe Illustrator), saving them as enhanced metafiles (.emf), and importing them into PowerPoint or Word. The results are (nearly) perfect! The only flaws I have identified so far is that semi-transparent colors become opaque and some lines with flat endings become lines with rounded endings. In most cases, I am very satisfied with the results.
Also, enhanced metafiles usually have extremely large file sizes when made in PowerPoint. However, when made in R the .emf file sizes have been very reasonable.
Assessing Psyche, Engaging Gauss, Seeking Sophia 
I found the same solution as you, long ago. I stumbled upon this page while hoping to find some way to turn anti-aliasing on in Office programs. Thanks for sharing this article; it isn’t what I wanted but it would have saved me a lot of time if I had read it last year. Inkscape is how I draw charts and they come out a lot better than if I had drawn them with my lower degree of powerpoint skils.
Another option is to use the ReporteRs package. It generates vector graphics that can be edited in Word or PowerPoint. It isn’t always perfect, but I have been able to get very good images using it.
I also found that using the ReporteRs package is much better to export R graphs to Powerpoint directly in native Office format – they are vector format, look perfect, are fully editable and also support transparency, unlike the solution above – see also my answer here: http://stackoverflow.com/questions/10497261/is-there-a-command-to-export-the-current-plot-from-rstudio – base R plots, lattice plots and ggplot2 are all supported
I now wrapped some functions to export R graphs to Powerpoint in fully editable vector format in a new package export – it just came out on CRAN, see https://cran.r-project.org/web/packages/export/index.html and https://github.com/tomwenseleers/export
Nice!