The 2006 Roth IRA contibution limit is $4000. This is the same as it was in 2005.
If you are over 50 years old, you may also contribute an extra $1000 as that is the 2006 catch-up contribution limit. This is the same as it was in 2005.

Roth IRA Contribution Limits

Year Maximum Regular IRA Contribution Catch-up Contribution
2002 $3000 $500
2003 $3000 $500
2004 $3000 $500
2005 $4000 $500
2006 $4000 $1000
2007 $4000 $1000
2008 $5000 $1000