IKWYM
When you do a download now, it starts by downloading the file procurve_firmware.prp to your download folder. If you look inside that file, you will see that HP does not update it as frequently as they do the swi files. The only way to override it is to modify that file so that PCM+ will make use of newer swi files. IMHO, it is not a very user friendly way to have to do it. If you have lots of switches to update, it may be worth it but I choose not to bother.
I only have 8 switches to upgrade so I just copy the swi file into the download folder and and telnet to them and invoke the command:
copy tftp flash 10.20.30.40 E_09_22.swi primary
I would like to hear again, HP's explanation. I opened an incident once on this but did not get a good reason why HP doesn't publish every version in the prp file. I'm supposed to get news of the PCM 2 beta next week, so if I get the chance, I will ask the beta team about this.