<PAGE>
                                                                       Ex. 10.28

      ACKNOWLEDGEMENT LETTER FOR PARTICIPATION OF EQUITY PLEDGE AGREEMENT

SHANGHAI FOCUS MEDIA ADVERTISEMENT CO., LTD., a limited liability company
(registered address: F Room 1003, No.1027, Changning Road, Changning District,
Shanghai)(hereinafter, "PARTICIPATED PLEDGOR") and SHENZHEN BIANJIE BUILDING
ADVERTISEMENT CO., LTD. (registered address: Room 1020, A, Wangxing Square, 38
Hongli Rd., Shenzhen) (hereinafter, "PARTICIPATED TARGET COMPANY") hereby agree
to participate in Equity Pledge Agreement dated on March 28, 2005 between FOCUS
MEDIA TECHNOLOGY (SHANGHAI) CO., LTD. (hereinafter "FOCUS MEDIA TECHNOLOGY"),
FOCUS MEDIA DIGITAL INFORMATION TECHNOLOGY (SHANGHAI) CO, LTD (hereinafter
"FOCUS MEDIA DIGITAL"), SHANGHAI FOCUS MEDIA ADVERTISEMENT CO., LTD. and other
relevant parties (hereinafter, "EQUITY PLEDGE AGREEMENT") as an independent
contract party. Participated Pledgors and Participated Target Companies pledge
the equity of the Participated Target Companies which constitute 99% of the
registered capital of the Participated Target Companies to Focus Media
Technology as the date of the Acknowledgement Letter to secure the following
contractual obligations:

1.   Contractual Obligation for the Participated Pledgeor:

(a)  Contractual Obligation under the Call Option Agreement among Focus Media
     Technology and other relevant parties dated March 28 2005 participated by
     the Pledgor pursuant to the Acknowledge Letter dated January 13 2006;

(b)  Contractual Obligation under the Shareholder's Voting Rights Proxy
     Agreement among Focus Media Technology and other relevant parties dated
     March 28 2005 participated by the Pledgor pursuant to the Acknowledge
     Letter dated January 13 2006;

2.   Contractual Obligation for the Participated Target Company:

(a)  Contractual Obligation under the Call Option Agreement participated by the
     Target Company pursuant to the Acknowledge Letter dated January 13 2006;

(b)  Contractual Obligation under the Shareholder's Voting Rights Proxy
     Agreement participated by the Target Company pursuant to the Acknowledge
     Letter dated January 13 2006;


                                        1

<PAGE>

This Acknowledgement Letter once executed by the Participated Pledgors and
Participated Target Company, Participated Pledgors and Participated Target
Companies shall make the same undertakings and warranties with those of Pledgors
and Target Companies under the Equity Pledge Agreement, agree to perform the
obligations of Pledgors and Target Company stipulated in the Equity Pledge
Agreement, and admit the rights and obligations of Parties under the Equity
Pledge Agreement.

SHANGHAI FOCUS MEDIA ADVERTISEMENT CO.,
LTD.
(Company chop)


Signature by: /s/ Jason Nanchun Jiang
              --------------------------
Name: Jason Nanchun Jiang
Position: Legal Representative
Date: January 13, 2006


SHENZHEN BIANJIE BUILDING ADVERTISEMENT
CO., LTD.
(Company chop)


Signature by: /s/ Jason Nanchun Jiang
              --------------------------
Name: Jason Nanchun Jiang
Position: Legal Representative
Date: January 13, 2006


FOCUS MEDIA TECHNOLOGY (SHANGHAI) CO.,
LTD.
(Company chop)


Signature by: /s/ Jason Nanchun Jiang
              --------------------------
Name: Jason Nanchun Jiang
Position: Legal Representative
Date: January 13, 2006


FOCUS MEDIA DIGITAL INFORMATION
TECHNOLOGY (SHANGHAI) CO, LTD
(Company chop)


Signature by: /s/ Jason Nanchun Jiang
              --------------------------
Name: Jason Nanchun Jiang
Position: Legal Representative
Date: January 13, 2006


                                        2