It seems that more people are learning about Scala. At JavaOne 2009, three of the books about Scala were in the Top Ten best sellers at the conference.
- 5th Programming in Scala
- 8th The Definitive Guide to Lift
- 9th Beginning Scala
Here's one report with more details.
This review of Beginning Scala is indicative of the quality and general appeal of the books, while Programming in Scala draws many recommendations in Amazon Customer reviews .