The second estimated tax payment for 2010 is due on 6/15/2010. Both state and federal taxes are due on the same day. Most states and the IRS are no longer sending out paper estimated tax forms.
A fillable Form 1040-ES for your federal taxes is available here: www.irs.gov/pub/irs-pdf/f1040es.pdf
The CT 1040-es can be downloaded from: www.ct.gov/drs/lib/drs/forms/2010forms/ct-1040es.pdf