http://blockchain.info/strange-transactions
The page is nearly useless because "real" strange Tx are lost among the huge P2Pool generation/coinbase Tx's.
On that page, you will see a bunch of large Tx with the last output unable to be decoded. You can know these Tx are from P2Pool by looking at the last two outputs (example, scroll to bottom of page):
http://blockchain.info/tx/abf4749cad03660deaace40b25a2f1d3e441c4c0bbef7682386984c2f5b7955b
The 2nd to last output is always a donation to the P2P donation address, 1Kz5QaUPDtKrj5SqW5tFkn7WZh8LmQaQi4. This is seen as an output to a public key rather than the address itself:
Code:
04ffd03de44a6e11b9917f3a29f9443283d9871c9d743ef30d5eddcd37094b64d1b3d8090496b53256786bf5c82932ec23c3b74d9f05a6f95a8b5529352656664b OP_CHECKSIG
The last output is always 0-valued and has an invalid script which is used internally by P2Pool (just a hash of some data), documented here. It is this output that is marked as strange.
I suggest that these Tx be removed from the Strage Transactions page. I think such a page is useful for looking at innovative uses for Bitcoin or learning about Tx scripting. With P2Pool Tx in there, it is hard to find other strange Tx. Perhaps exclude "garbage" output scripts which don't have any valid opcodes from being marked as strange, or just exclude generation Tx which send to the P2Pool donation public key.