A Google developer Scott Savage has coded and launched a simple web app that allows you to easily migrate your photos stored on Flickr to Google Plus.

The service ensures that important metadata information including Titles and Geodata is preserved during the migration process. In fact following data is preserved:

Title
Description/summary
Tags
Commenting permissions
Upload timestamp
Geo location

The web app does not require downloading the photos to your computer as most other apps require.

There are some limitations though. Videos are not exported. Image specific permissions are lost as Picasa does not allow that. It also convert RAW and TIFF images to JPEGs. Comments are also not migrated as they are connected to Yahoo account.

If you do not have paid storage on Picasa, the app would store images in the free size limit (2048 pixels) once the free storage is utilized.