I think the problem may be due to reindexing of photos and media, which keeps on running until all files have been indexed and therefore may cause both temperature increase and faster battery drain. Once it has finished, the problems should go away. I noticed my N900 getting warmer, but just for the first day after upgrade. I checked by opening xterminal and running command top In the %CPU column there were high values for tracker-indexer and hildon-thumbnail.