Npgsql 2.2.5 has just been released and is available via nuget.
This is an important bugfix release, everyone should upgrade. Particularly important is a leak due to an EntityFramework issue (#505), thanks @havard.
This release also includes several changes to make Npgsql work well with Amazon Redshift. Support isn't perfect yet but should be considerably better than before, please report any further issues.
The full list of fixes can be found here.
Note: 2.2.5.0-r2 setups use Npgsql DLL files from official release. 2.2.5.0 doesn't.
Note: 2.2.5.0-r3 setups register Mono.Security.dll to GAC correctly. 2.2.5.0-r2 doesn't.