Update: I can confirm the save works even on accounts and PS3's that do not have the Summer House installed. I removed all Save data Game data and Home data. After I reinstalled home, copied the exploit save over and booted up Home it asked me to download the Summerhouse and install it. Viola!
Note you can't teleport to it via PDA but can enter it via Central Plaza (Home Square) etc.
Download: PS Home Summer House Save Glitch [Right-click, Save As]
I have discovered that when I copied my main PSN account Home Settings save over to my other master accounts and I had the default Home space set to the Summerhouse it remained that way and when I logged into home I appeared in the Summerhouse (which I only purchased with my main PSN account). ;)
I have built a save for you all to try out. It has been tested with US, Euro, HK and Jap accounts and works with all accounts and PS3's that do not have the Summer House installed. Read me for install notes included in .rar file.
More PlayStation 3 News...