Perhaps a good indication of its suitability for "big data" is the fact that R has emerged as the platform of choice for developers competing in Kaggle.com data modeling competitions. See the article on the Revolution Analytics website -- R beats out SAS and SPSS by a healthy margin. What R lacks in out of the box number crunching power it apparently makes up for in flexibility.
In addition to what's available on the web there are several new books for how to hot-rod R for tackling big data. The Art of R Programming (Matloff 2011; No Starch Press) provide introductions to writing optimized R code, parallel computing, and using R in conjunction with C. The entire book is well-written with great code samples and walk-throughs. Parallel R (McCallum & Weston 2011; O'Reilly) looks good too.
