Sometimes you need a stat for a presentation, whitepaper, article or blog post.  EmailStatCenter.com has tons of email marketing stats.  Here are some recent ones you can use as long as you provide appropriate attribution.

62% of email traffic share to landing pages comes from Yahoo! Mail, while Gmail provides just 4% of referrals.
- Chitika Insights (2011)

US adult internet users subscribe to an average of almost three daily or weekly shopping emails or newsletters.
- Yahoo! Mail and Ipsos OTX MediaCT, "Consumer Pulse" (2011)

Q4 2010 open rates (22.1%) saw little change over the two-year period, increasing 5% from the same time two years ago.
- Epsilon and eec "Q4 2010 Email Trends and Benchmarks" (2011)

Email has been used by nearly 90% of consumers since 2005.
- MarketingProfs, "2010 Digital Marketing Fact Book"