One of my SoC students is working on a grammar-checking plugin for AbiWord. Last week, he started to use ICU's sentence breaker instead of an ad-hoc one that we'd developed inside of AbiWord. The major difference is in how abbreviations (like "Mr." and "Mrs.") are handled. The results aren't perfect, but he's making headway.

Obligatory before and after screenshots, for Uwog's viewing pleasure.