Yes, the Heartland Institute (and all other organizations) raise money from supporters to pay for work to advance its agenda. This is not Climategate-in-reverse.
The Register (UK) reports:
Gifted amateurs and interested activists the world over are poring over documents published on the Desmog blog and elsewhere, which appear to detail the US think-tank the Heartland Institute’s budget and anti-climate-change strategy.
A list of the documents can be found on Skeptical Science, here (I am referring to this list rather than others now available because some sites, such as ThinkProgress, appear to be suffering occasional DoS-by-popularity).
If, as they are described, these are genuine Heartland internal documents, the leak is at least as good as the “climategate” e-mails…
Climategate was better because those e-mails proved bad intent on the part of alarmists, not mere raising and distribution of funds.